candidate mechanisms of electron pairing near EF at T=0, binding energy of the electron pairs thus formed, and superconductivity in mono-atom crystals have been proposed.
Once EM wave modes are established in the ranges of their associated lattice chains of a crystal concerned, which ranges can be long or even macroscopic, electron-pairs are produced in the crystal’s electron system over these ranges. As EM wave modes with frequencies below certain value (corresponding to an energy value Δ) may have little contribution to stimulated transitions of electrons and electron-pairing, at T=0 each of the electrons at and near EF pairs with one of the electrons at energy levels of EF-hωM/(2π)≤E≤EF-Δ (where ωM is the maximum frequency of lattice wave modes of the system, which is often associated with a specific crystal orientation), resulting in a binding energy of at least Δ for each of these pairs at T=0.
candidate mechanisms of electron pairing near EF at T=0, binding energy of the electron pairs thus formed, and superconductivity in mono-atom crystals have been proposed.
Once EM wave modes are established in the ranges of their associated lattice chains of a crystal concerned, which ranges can be long or even macroscopic, electron-pairs are produced in the crystal’s electron system over these ranges. As EM wave modes with frequencies below certain value (corresponding to an energy value Δ) may have little contribution to stimulated transitions of electrons and electron-pairing, at T=0 each of the electrons at and near EF pairs with one of the electrons at energy levels of EF-hωM/(2π)≤E≤EF-Δ (where ωM is the maximum frequency of lattice wave modes of the system, which is often associated with a specific crystal orientation), resulting in a binding energy of at least Δ for each of these pairs at T=0.
electron pairing and mechanism of superconductivity in ionic crystals Qiang LI
The behaviors of valence electrons and ions, particularly ion chains, in ionic crystals are important to understanding of the mechanism of superconductivity. The author has made efforts to establish a candidate mechanism of electron-pairing and superconductivity in ionic crystals.
Analyses are first made to a one-dimensional long ion lattice chain model (EDP model), with the presence of lattice wave modes having frequency ω. A mechanism of electron pairing is established.
Analyses are then extended to scenarios of 3D ionic crystals, particularly those with a donor/acceptor system, with emphasis being given to the interpretation and understanding of binding energy of electron pairs formed between electrons at the top/bottom of donor/acceptor band and the bottom/top of conducting/full band.
It is established that once the lattice/EM wave modes are established in its range, which can be long or even macroscopic, electron pairs are produced in the crystal’s electron system over the same range by stimulated transitions induced by the EM wave mode. The lattice wave mode having the maximum frequency ωM is of special significance with respect to superconductivity, for electron pairs produced by it can be stabilized in the context of a combination of some special factors (including energy level structure featured by donor/acceptor band and ωM) with a binding energy typically no smaller than hωM/(2π). A candidate mechanism of electron pairing in ion crystals and therefore of superconductivity is provided.
Mechanism of electron pairing in crystals, with binding energy no smaller tha...Qiang LI
Establishment of mechanism of electron pairing with a lower limit of binding energy is necessary for understating of superconductivity. Due to conservation of wavevector, photon absorption/emission by an electron in crystal can only be allowed across at least on band gap, which is also true for virtual photon absorption/emission inducing electron pairing in crystal. Therefore, it is clearly explained that electron pairs, formed by virtual stipulated transition, can only exist between electrons across a band gap, with a binding energy no smaller than the width of the band gap.
candidate mechanisms of electron pairing near EF at T=0, binding energy of the electron pairs thus formed, and superconductivity in mono-atom crystals have been proposed.
Once EM wave modes are established in the ranges of their associated lattice chains of a crystal concerned, which ranges can be long or even macroscopic, electron-pairs are produced in the crystal’s electron system over these ranges. As EM wave modes with frequencies below certain value (corresponding to an energy value Δ) may have little contribution to stimulated transitions of electrons and electron-pairing, at T=0 each of the electrons at and near EF pairs with one of the electrons at energy levels of EF-hωM/(2π)≤E≤EF-Δ (where ωM is the maximum frequency of lattice wave modes of the system, which is often associated with a specific crystal orientation), resulting in a binding energy of at least Δ for each of these pairs at T=0.
electron pairing and mechanism of superconductivity in ionic crystals Qiang LI
The behaviors of valence electrons and ions, particularly ion chains, in ionic crystals are important to understanding of the mechanism of superconductivity. The author has made efforts to establish a candidate mechanism of electron-pairing and superconductivity in ionic crystals.
Analyses are first made to a one-dimensional long ion lattice chain model (EDP model), with the presence of lattice wave modes having frequency ω. A mechanism of electron pairing is established.
Analyses are then extended to scenarios of 3D ionic crystals, particularly those with a donor/acceptor system, with emphasis being given to the interpretation and understanding of binding energy of electron pairs formed between electrons at the top/bottom of donor/acceptor band and the bottom/top of conducting/full band.
It is established that once the lattice/EM wave modes are established in its range, which can be long or even macroscopic, electron pairs are produced in the crystal’s electron system over the same range by stimulated transitions induced by the EM wave mode. The lattice wave mode having the maximum frequency ωM is of special significance with respect to superconductivity, for electron pairs produced by it can be stabilized in the context of a combination of some special factors (including energy level structure featured by donor/acceptor band and ωM) with a binding energy typically no smaller than hωM/(2π). A candidate mechanism of electron pairing in ion crystals and therefore of superconductivity is provided.
Mechanism of electron pairing in crystals, with binding energy no smaller tha...Qiang LI
Establishment of mechanism of electron pairing with a lower limit of binding energy is necessary for understating of superconductivity. Due to conservation of wavevector, photon absorption/emission by an electron in crystal can only be allowed across at least on band gap, which is also true for virtual photon absorption/emission inducing electron pairing in crystal. Therefore, it is clearly explained that electron pairs, formed by virtual stipulated transition, can only exist between electrons across a band gap, with a binding energy no smaller than the width of the band gap.
Energy bands and electrical properties of metals newPraveen Vaidya
The chapter gives brief knowledge about formation of bands in solids. What are free electrons how they contribute for conductivity in conductors, but can be extended to semiconductors also.
Energy bands and electrical properties of metals newPraveen Vaidya
The chapter gives brief knowledge about formation of bands in solids. What are free electrons how they contribute for conductivity in conductors, but can be extended to semiconductors also.
Solid-state electrolytes exhibit good safety and stability, and are promising to replace current organic liquid electrolytes in rechargeable battery applications. In this talk, we will present our efforts at developing scalable first principles techniques to design novel solid-state electrolytes. Using the recently discovered Li10GeP2S12 lithium super ionic conductor as an example, we will discuss how various properties of interest in a solid-state electrolyte can be predicted using first principles calculations. We will show how the application of these first principles techniques has suggested two chemical modifications, Li10SiP2S12 and Li10SnP2S12, that retains the excellent Li+ conductivity of Li10GeP2S12 at a significantly reduced cost. These modifications have recently been synthesized, and the measured Li+ conductivities are in excellent agreement with our first principles predictions. We will conclude with a demonstration of how relatively expensive first principles calculations can be intelligently scaled and combined with topological analysis to be a useful screening tool for novel solid-state electrolytes.
phonon as carrier of electromagnetic interaction between lattice wave modes a...Qiang LI
The new results reported here mainly include: 1) recognition that phonon is carrier of electromagnetic interaction between its lattice wave mode and electrons; 2) recognition that binding energy of electron pairs of high-temperature superconductivity is due to escape of optical threshold phonons, of electron pairs at or near Fermi level, from crystal by direct radiation; 3) recognition that binding energy of electron pairs of low-temperature superconductivity is possibly due to escape of non-optical threshold phonons by anharmonic crystal interactions; and, 4) recognition of a possible mechanism explaining why some crystals never have a superconducting phase. While electron pairing is phonon-mediated in general, HTS should be associated with electron pairing mediated by optical phonon at or near Fermi level (EF), so the rarity of HTS corresponds to the rarity of such pairing match.
phonon as carrier of electromagnetic interaction between lattice wave modes a...Qiang LI
The new results reported here mainly include: 1) recognition that phonon is carrier of electromagnetic interaction between its lattice wave mode and electrons; 2) recognition that binding energy of electron pairs of high-temperature superconductivity is due to escape of optical threshold phonons, of electron pairs at or near Fermi level, from crystal by direct radiation; 3) recognition that binding energy of electron pairs of low-temperature superconductivity is possibly due to escape of non-optical threshold phonons by anharmonic crystal interactions; and, 4) recognition of a possible mechanism explaining why some crystals never have a superconducting phase. While electron pairing is phonon-mediated in general, HTS should be associated with electron pairing mediated by optical phonon at or near Fermi level (EF), so the rarity of HTS corresponds to the rarity of such pairing match.
Mechanism of electron pairing in crystals, with binding energy no smaller tha...Qiang LI
(A prepring publication)
Establishment of mechanism of electron pairing with a lower limit of binding energy is necessary for understating of superconductivity. Due to conservation of wavevector, photon absorption/emission by an electron in crystal can only be allowed across at least on band gap, which is also true for virtual photon absorption/emission inducing electron pairing in crystal. Therefore, it is clearly explained that electron pairs, formed by virtual stipulated transition, can only exist between electrons across a band gap, with a binding energy no smaller than the width of the band gap.
(v3) Phonon as carrier of electromagnetic interaction between vibrating latti...Qiang LI
With emphasis on time-dependency of electron-lattice system, we suggest the fallacy of presumed quantization in the context of electron-lattice system and propose the definition of phonons as carriers of electromagnetic interaction between electrons and vibrating lattice. We have investigated behaviors of electron-lattice system relating to “measured” energy, identified non-stationary steady state of electrons engaging in “electron pairing by virtual stimulated transitions”, recognized some origins of binding energy of electron pairs in crystals, and explained the state of electrons under pairing. Moreover, we have recognized the behavior and role of threshold phonon, which exists in electron pairing and is released by the electron from excited state, and have recognized the redundancy of the threshold phonon when the electrons under pairing have entered non-stationary steady state. We have also studied the effect of the stability of lattice wave on the evolution of the function of transition probability and on the stability of phonon-mediated electron pairs, the competition among multiple pairings associated with one same ground state, and determination of presence/absence of superconductivity by such competition.
A model of electron pairing, with depletion of mediating phonons at fermi sur...Qiang LI
We present a model of electron pairing based on nonstationary interpretation of electron-lattice interaction. Electron-lattice system has an intrinsic time dependent characteristic as featured by Golden Rule, by which electrons on matched pairing states are tuned to lattice wave modes, with pairing competition happening among multiple pairings associated with one electron state. The threshold phonon of an electron pair having a good quality factor can become redundant and be released from the pair to produce a binding energy. Lattice modes falling in a common linewidth compete with one another, like modes competing in a lasing system. In cuprates, due to near-parallel band splitting at and near Fermi Surface (EF), a great number of electron pairs are tuned to a relatively small number of lattice wave modes, leading to strong mode competition, transfer of real pairing-mediating phonons from EF towards the “kink”, and depletion of these phonons at and near EF.
A Mechanism Of Electron Pairing Relating To SupperconductivityQiang LI
Mechanism of superconductivity is based on a mechanism of electron pairing near EF with definite binding energy. A candidate mechanism of such electron pairing is described in this paper. Electron pairs are induced by EM wave modes generated by corresponding lattice wave modes. The pairs are formed between E(k) faces from different Brillouin zones, with definite binding energies. The binding energy of an electron pair is characterized by the frequency of the EM mode that induces the pairing.
For UG students of All Engineering Branches (Mechanical Engg., Chemical Engg., Instrumentation Engg., Food Technology) and PG students of Chemistry, Physics, Biochemistry, Pharmacy
The link of the video lecture at YouTube is
https://www.youtube.com/watch?v=t3QDG8ZIX-8
because Electron Affinity is the amount of energy.pdfinfo518726
because Electron Affinity is the amount of energy needed to add an electron to an
atom or molecule.. Thus Decreasing its Stabillity and Whenever We have Decrease in Stability
We Have A Negative Energy Released thus energy required and hence negative electron
affinity..The Electron affinity of an atom or molecule is defined as the amount of energy released
when an electron is added to a neutral atom or molecule to form a negative ion. X + e- ? X-
(note: the correct equation in words is X + electron -> X + energy) This property is measured for
atoms and molecules in the gaseous state only, since in the solid or liquid states their energy
levels would be changed by contact with other atoms or molecules. A list of the electron
affinities was used by Robert S. Mulliken to develop an electronegativity scale for atoms, equal
to the average of the electron affinity and ionization potential.Other theoretical concepts that use
electron affinity include electronic chemical potential and chemical hardness. Another example,
a molecule or atom that has a more positive value of electron affinity than another is often called
an electron acceptor and the less positive an electron donor. Together they may undergo charge-
transfer reactions. In solids, the electron affinity is the energy difference between the vacuum
energy and the conduction band minimum. To use electron affinities properly, it is essential to
keep track of sign. For any reaction that releases energy, the change in energy, ?E, has a negative
value and the reaction is called an exothermic process. Electron capture for almost all non-noble
gas atoms involves the release of energy and thus are exothermic. The positive values that are
listed in tables of Eea are amounts or magnitudes. It is the word, released within the definition
energy released that supplies the negative sign. Confusion arises in mistaking Eea for a change in
energy, ?E, in which case the positive values listed in tables would be for an endo- not exo-
thermic process. The relation between the two is, Eea = - ?E(attach). However, if the value
assigned to Eea is negative, the negative sign implies a reversal of direction, and energy is
required to attach an electron. In this case, the electron capture is an endothermic process and the
relationship, Eea = - ?E(attach) is still valid. Negative values typically arise for the capture of a
second electron, but also for the nitrogen atom. The usual expression for calculating Eea when
an electron is attached is Eea = (Einitial - Efinal)attach = - ?E(attach) This expression does
follow the convention ?X = X(final) - X(initial) since - ?E = - (E(final) - E(initial)) = E(initial) -
E(final). Equivalently, electron affinity can also be defined as the amount of energy required to
detach an electron from a singly charged negative ion,i.e. the energy change for the process X- ?
X + e- If the same table is employed for the forward and reverse reactions, without switching
signs, care must be take.
Similar to Mechanism Of Superconductivity In Metals (20)
Solutions of Maxwell Equation for a Lattice System with Meissner EffectQiang LI
We show that Maxwell equation of a lattice system may have Meissner effect solutions when all carriers are surface state electrons. Some limitations on the wave function distributions of electrons in the system are identified.
Microscopic Mechanisms of Superconducting Flux Quantum and Superconducting an...Qiang LI
We have provided microscopic explanations to superconducting flux quantum and (superconducting and normal) persistent current. Flux quantum is generated by current carried by "deep electrons" at surface states. And values of the flux quantum differs according to the electronic states and coupling of the carrier electrons. Generation of persistent carrier electrons does not dissipate energy; instead there would be emission of real phonons and release of corresponding energy into the environment; but the normal carrier electrons involved still dissipate energy. Even for or persistent carriers,there should be a build-up of energy of the middle state and a build-up of the probability of virtual transition of electrons to the middle state, and the corresponding relaxation should exist accordingly.
Energy gap as a measure of pairing instability, Bogoliubov quasiparticles as ...Qiang LI
The magnitude of an apparent energy gap is recognized as a measure of relative instability of electron pairing at the gap location, for it indicates that stabilized pairing can only be realized at a greater binding energy. At a low temperature, the chemical potential of a system like Bi2212 is determined by the most stable pairing, and will drop by about the energy of the mediating mode when pairing is stable. Bogoliubov quasiparticles are explained as excitations by lattice modes that win a mode competition among mediating modes and therefore have a large number of phonons depleted from losing modes. Thus, the energy of BQP peak is that of upper states of pairs mediated by the winning modes (~70 meV), while the energy of the nodal kink is that of the base states of these pairs, which shifts upward due to band topology on leaving the node. The “superconducting gap” corresponds to a kinked band section, a kink at the lower edge of which varnishes as nodal gap transform into the antinodal one.
Energy scale in ARPES data suggesting Bogoliubov quasiparticles as excitation...Qiang LI
A dip is identified in existing ARPES spectra of Bi2223. The energy separation between the dip and Bogoliubov (BQP) peak is well-defined at a value of about 68 meV. More remarkably, it is shown that, with a lattice-mode-specific modification detailed below, the strength of the dip is in well qualitative agreement with that of the BQP peak. These results strongly suggest an origin of BQPs as excitations by phonons of a very small number of lattice modes, which could be a direct clue to understanding the interactions leading to nodal and antinodal energy gap features and even high-temperature superconductivity itself.
Explaining cuprates antinodal psuedogap features lq111203Qiang LI
We provide an explanation of anti-nodal pseudogap features of cuprates on the basis of a proposed electron pairing model, and recognize the bosonic modes responsible for electron pairings leading to the anti-nodal pseudogap features, as having and energy range estimated at about 25-30 meV.
candidate mechanisms of electron pairing near EF at T=0, binding energy of the electron pairs thus formed, and superconductivity in mono-atom crystals have been proposed.
Once EM wave modes are established in the ranges of their associated lattice chains of a crystal concerned, which ranges can be long or even macroscopic, electron-pairs are produced in the crystal’s electron system over these ranges. As EM wave modes with frequencies below certain value (corresponding to an energy value Δ) may have little contribution to stimulated transitions of electrons and electron-pairing, at T=0 each of the electrons at and near EF pairs with one of the electrons at energy levels of EF-hωM/(2π)≤E≤EF-Δ (where ωM is the maximum frequency of lattice wave modes of the system, which is often associated with a specific crystal orientation), resulting in a binding energy of at least Δ for each of these pairs at T=0.
Builder.ai Founder Sachin Dev Duggal's Strategic Approach to Create an Innova...Ramesh Iyer
In today's fast-changing business world, Companies that adapt and embrace new ideas often need help to keep up with the competition. However, fostering a culture of innovation takes much work. It takes vision, leadership and willingness to take risks in the right proportion. Sachin Dev Duggal, co-founder of Builder.ai, has perfected the art of this balance, creating a company culture where creativity and growth are nurtured at each stage.
Key Trends Shaping the Future of Infrastructure.pdfCheryl Hung
Keynote at DIGIT West Expo, Glasgow on 29 May 2024.
Cheryl Hung, ochery.com
Sr Director, Infrastructure Ecosystem, Arm.
The key trends across hardware, cloud and open-source; exploring how these areas are likely to mature and develop over the short and long-term, and then considering how organisations can position themselves to adapt and thrive.
State of ICS and IoT Cyber Threat Landscape Report 2024 previewPrayukth K V
The IoT and OT threat landscape report has been prepared by the Threat Research Team at Sectrio using data from Sectrio, cyber threat intelligence farming facilities spread across over 85 cities around the world. In addition, Sectrio also runs AI-based advanced threat and payload engagement facilities that serve as sinks to attract and engage sophisticated threat actors, and newer malware including new variants and latent threats that are at an earlier stage of development.
The latest edition of the OT/ICS and IoT security Threat Landscape Report 2024 also covers:
State of global ICS asset and network exposure
Sectoral targets and attacks as well as the cost of ransom
Global APT activity, AI usage, actor and tactic profiles, and implications
Rise in volumes of AI-powered cyberattacks
Major cyber events in 2024
Malware and malicious payload trends
Cyberattack types and targets
Vulnerability exploit attempts on CVEs
Attacks on counties – USA
Expansion of bot farms – how, where, and why
In-depth analysis of the cyber threat landscape across North America, South America, Europe, APAC, and the Middle East
Why are attacks on smart factories rising?
Cyber risk predictions
Axis of attacks – Europe
Systemic attacks in the Middle East
Download the full report from here:
https://sectrio.com/resources/ot-threat-landscape-reports/sectrio-releases-ot-ics-and-iot-security-threat-landscape-report-2024/
UiPath Test Automation using UiPath Test Suite series, part 4DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 4. In this session, we will cover Test Manager overview along with SAP heatmap.
The UiPath Test Manager overview with SAP heatmap webinar offers a concise yet comprehensive exploration of the role of a Test Manager within SAP environments, coupled with the utilization of heatmaps for effective testing strategies.
Participants will gain insights into the responsibilities, challenges, and best practices associated with test management in SAP projects. Additionally, the webinar delves into the significance of heatmaps as a visual aid for identifying testing priorities, areas of risk, and resource allocation within SAP landscapes. Through this session, attendees can expect to enhance their understanding of test management principles while learning practical approaches to optimize testing processes in SAP environments using heatmap visualization techniques
What will you get from this session?
1. Insights into SAP testing best practices
2. Heatmap utilization for testing
3. Optimization of testing processes
4. Demo
Topics covered:
Execution from the test manager
Orchestrator execution result
Defect reporting
SAP heatmap example with demo
Speaker:
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
Observability Concepts EVERY Developer Should Know -- DeveloperWeek Europe.pdfPaige Cruz
Monitoring and observability aren’t traditionally found in software curriculums and many of us cobble this knowledge together from whatever vendor or ecosystem we were first introduced to and whatever is a part of your current company’s observability stack.
While the dev and ops silo continues to crumble….many organizations still relegate monitoring & observability as the purview of ops, infra and SRE teams. This is a mistake - achieving a highly observable system requires collaboration up and down the stack.
I, a former op, would like to extend an invitation to all application developers to join the observability party will share these foundational concepts to build on:
Generative AI Deep Dive: Advancing from Proof of Concept to ProductionAggregage
Join Maher Hanafi, VP of Engineering at Betterworks, in this new session where he'll share a practical framework to transform Gen AI prototypes into impactful products! He'll delve into the complexities of data collection and management, model selection and optimization, and ensuring security, scalability, and responsible use.
Welocme to ViralQR, your best QR code generator.ViralQR
Welcome to ViralQR, your best QR code generator available on the market!
At ViralQR, we design static and dynamic QR codes. Our mission is to make business operations easier and customer engagement more powerful through the use of QR technology. Be it a small-scale business or a huge enterprise, our easy-to-use platform provides multiple choices that can be tailored according to your company's branding and marketing strategies.
Our Vision
We are here to make the process of creating QR codes easy and smooth, thus enhancing customer interaction and making business more fluid. We very strongly believe in the ability of QR codes to change the world for businesses in their interaction with customers and are set on making that technology accessible and usable far and wide.
Our Achievements
Ever since its inception, we have successfully served many clients by offering QR codes in their marketing, service delivery, and collection of feedback across various industries. Our platform has been recognized for its ease of use and amazing features, which helped a business to make QR codes.
Our Services
At ViralQR, here is a comprehensive suite of services that caters to your very needs:
Static QR Codes: Create free static QR codes. These QR codes are able to store significant information such as URLs, vCards, plain text, emails and SMS, Wi-Fi credentials, and Bitcoin addresses.
Dynamic QR codes: These also have all the advanced features but are subscription-based. They can directly link to PDF files, images, micro-landing pages, social accounts, review forms, business pages, and applications. In addition, they can be branded with CTAs, frames, patterns, colors, and logos to enhance your branding.
Pricing and Packages
Additionally, there is a 14-day free offer to ViralQR, which is an exceptional opportunity for new users to take a feel of this platform. One can easily subscribe from there and experience the full dynamic of using QR codes. The subscription plans are not only meant for business; they are priced very flexibly so that literally every business could afford to benefit from our service.
Why choose us?
ViralQR will provide services for marketing, advertising, catering, retail, and the like. The QR codes can be posted on fliers, packaging, merchandise, and banners, as well as to substitute for cash and cards in a restaurant or coffee shop. With QR codes integrated into your business, improve customer engagement and streamline operations.
Comprehensive Analytics
Subscribers of ViralQR receive detailed analytics and tracking tools in light of having a view of the core values of QR code performance. Our analytics dashboard shows aggregate views and unique views, as well as detailed information about each impression, including time, device, browser, and estimated location by city and country.
So, thank you for choosing ViralQR; we have an offer of nothing but the best in terms of QR code services to meet business diversity!
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📕 Vedremo insieme alcuni esempi dell'utilizzo di Autopilot in diversi tool della Suite UiPath:
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Autopilot per Studio
Autopilot per Apps
Clipboard AI
GenAI applicata alla Document Understanding
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GraphRAG is All You need? LLM & Knowledge GraphGuy Korland
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https://arxiv.org/abs/2306.08302
2. Microsoft Research's GraphRAG paper and a review paper on various uses of knowledge graphs:
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Clients don’t know what they don’t know. What web solutions are right for them? How does WordPress come into the picture? How do you make sure you understand scope and timeline? What do you do if sometime changes?
All these questions and more will be explored as we talk about matching clients’ needs with what your agency offers without pulling teeth or pulling your hair out. Practical tips, and strategies for successful relationship building that leads to closing the deal.
By Design, not by Accident - Agile Venture Bolzano 2024
Mechanism Of Superconductivity In Metals
1. (PACS: 74.20.Mn 74.25.F- )
(Keywords: mechanism of binding energy of electron pair at T=0, mechanism of
superconductivity of metals, electron pairing, low-temperature superconductivity)
Mechanism of superconductivity in metals
Author: Q. LI
Affiliation: JHLF
Finish date: 08 Match 2010
Abstract
It has been established [1] that at least some valence electrons in lattice may
undergoes constant virtual stimulated transitions driven by EM wave modes coupled
to and produced by corresponding lattice wave modes. Do and how do such virtual
stimulated electron transitions have something to do with electron-pairing and
mechanism of superconductivity in mono-atom crystals like metals?
With efforts made by the author in addressing these questions, candidate
mechanisms of electron pairing near EF at T=0, binding energy of the electron pairs
thus formed, and superconductivity in mono-atom crystals have been proposed.
Once EM wave modes are established in the ranges of their associated lattice
chains of a crystal concerned, which ranges can be long or even macroscopic,
electron-pairs are produced in the crystal’s electron system over these ranges. As EM
wave modes with frequencies below certain value (corresponding to an energy value
∆) may have little contribution to stimulated transitions of electrons and
electron-pairing, at T=0 each of the electrons at and near EF pairs with one of the
electrons at energy levels of EF-hωM/(2π)≤E≤EF-∆ (where ωM is the maximum
frequency of lattice wave modes of the system, which is often associated with a
specific crystal orientation), resulting in a binding energy of at least ∆ for each of
these pairs at T=0.
Therefore, for mono-atom crystals, the critical parameter like Tc is related to
the characteristics of lattice/EM wave modes, particularly the strength of the EM
wave modes at ω→0.
Introduction
It has been established [1] that at least some valence electrons in lattice may
undergo constant virtual stimulated transitions driven by EM wave modes coupled to
and produced by corresponding lattice wave modes. Do and how do such virtual
stimulated electron transitions have something to do with electron-pairing and
mechanism of superconductivity in mono-atom crystals like metals?
With efforts made by the author in addressing these questions, candidate
mechanisms of electron pairing near EF at T=0, binding energy of the electron pairs
thus formed, and superconductivity in mono-atom crystals have been proposed.
1
2. It has been established [1] that some valence electrons in lattice may undergoes
constant virtual stimulated transitions driven by EM wave modes coupled to and
produced by corresponding lattice wave modes.
Stimulated transitions and pairing of electrons
Generally speaking, if an electron is driven by an EM wave mode to perform
stimulated transition, a photon is to be associated with the transition. However, if a
pair of electrons, at energy levels of En and Ek respectively, are driven by an EM wave
mode of frequency of Enk=En-Ek=±hω/(2π) to perform stimulated transitions by
exchanging their states with each other, neither photon emission nor photon
absorption will happen in real, instead a virtual exchange of one photon of
Enk=±hω/(2π) happens between these two electrons. This is the “electron pairing”
under the presence of EM wave modes.
In mono-atom systems like metals, there are no optical lattice wave modes, and
only acoustic lattice wave modes (LA and TA modes) exist. These vibrations of atom
cores cause deviation of charge distribution of positive atom cores with respect to the
background of a sea of negative valence electrons, which results in vibrating dipoles
and corresponding EM wave modes. As each lattice wave mode in all crystals is
directly coupled to an EM wave mode of the same frequency, such “electron pairing”
under stimulated transition is omnipresent in all crystals.
Since at q→0 the vibrations of neighboring atoms in mono-atom system go to in
phase and the frequency of the vibrations go to zero [2], the low frequency
components of the LA and TA modes of lattice produce almost no oscillating EM
waves.
When two electrons, at En and Ek respectively, are paired with each other under
stimulated transitions generated by an EM wave mode of hω/(2π)=En-Ek, they are
bound by one photon of hω/(2π)=En-Ek; or in other words, the two electrons bind the
photon between them.
For the system of ψ(t)=U(t,t0)ψ(t0) as concerned, as indicated by [1]:
k1
a n ∝Σ(exp(i(2πEnk+hωm)t/h)/( hωm/+2πEnk)-exp(-i(2πEnk-hωm)t/h)/(hωm-2πEnk)
(Equ. 1-3)
(where ωm are the frequencies of the lattice wave modes, m=1, 2, 3…..denotes the
different lattice/EM wave modes of the ion chains,) a nk1 converges to Enk=±hωm/(2π)
along with time t, so after sufficient time t, almost all electrons in the system will
perform stimulated transitions with Enk=±hωm/(2π), that is:
a nk1 →ΣAmδ(Enk-hωm/(2π)),
and Am corresponds to the probability of transitions corresponding to hωm/(2π).
Obviously, Am is proportional to the strength of EM wave mode of ωm. However,
as was established with a one-dimensional lattice model [2] and with experimental
result [3], at the limit of ω→0 (q→0), the vibrations of the atom cores go to in phase
so their EM wave modes also goes to zero. Thus, the probabilities of transitions
corresponding to EM wave modes with ω→0 go to zero. In other words, an energy
value ∆ can be set, with only transitions of Enk=±hωm/(2π)≥±∆ actually happening in
the system (no matter it is a mono-, bi- or multi-atom system).
2
3. Electron-pairing in metals at T=0
Considering now for T=0, with a nk1 →Σδ(Enk-hωm/(2π)) after sufficient time t,
only transitions with En-Ek= hωm/(2π)≥±∆ will exist in the system after sufficient time
t. So each of the electrons at E=EF will pair with an electron at an energy level E of
EF-hωM/(2π)≤E≤EF-∆, where ωM is the maximum frequency of all the lattice wave
modes present in the system. Taking E=0, the energy of the pair is ∆.
Thus, if such an electron pair is broken at T=0, the energy of the exiting
electron will be >∆, and that of the remaining electron will be ∆ (for the remaining
electron is still in its state as before the pair is broken and is to make its upward
transition at the moment, so a photon of energy ∆ is with the remaining electron). So
this electron pair has a binding energy of >∆ at T=0.
The minimum binding energy for an electron pair including an electron near and
below EF is (slightly) greater accordingly. Thus, electrons at and near EF are all in
pairs each having a binding energy of >∆.
The electrons at and near EF at T=0 are those contributing to conductivity.
Conclusion
Once EM wave modes are established in the ranges of their associated lattice
chains of a crystal concerned, which ranges can be long or even macroscopic,
electron-pairs are produced in the crystal’s electron system over these ranges. As EM
wave modes with frequencies below certain value (corresponding to an energy value
∆) may have little contribution to stimulated transitions of electrons and
electron-pairing, at T=0 each of the electrons at and near EF pairs with one of the
electrons at energy levels of EF-hωM/(2π)≤E≤EF-∆ (where ωM is the maximum
frequency of lattice wave modes of the system, which is often associated with a
specific crystal orientation), resulting in a binding energy of at least ∆ for each of
these pairs at T=0.
For temperature not too far from T=0, sufficient electron pairs can still be
maintained, so can be the state of superconductivity.
Therefore, for mono-atom crystals, the critical parameter like Tc is related to
the characteristics of lattice/EM wave modes, particularly the strength of the EM
wave modes at ω→0.
[1] “Electron-pairing in ionic crystals and mechanism of superconductivity”, by: Q.
LI,JHLF,
http://www.slideshare.net/edpmodel/100304-affi-electron-pairing-in-ionic-crystals-an
d-mechanism-of-superconductivity#
[2] “Solid State Physics”, by Prof. HUANG Kun, published (in Chinese) by People’s
Education Publication House, with a Unified Book Number of 13012.0220, a
publication date of June 1966, and a date of first print of January 1979, page 106,
Equ. 5-40.
[3] See [2], Fig. 5-12, page 113.
3