This document provides an overview of group theory concepts. A group is a collection of elements that is closed under a binary operation, contains an identity element, and has inverse elements. Groups can be represented by multiplication tables. Symmetry operations within a point group can be classified into conjugacy classes based on their similarity transforms. Matrix representations allow symmetry operations to be modeled as transformations on object coordinates.
A ppt compiled by Yaseen Aziz Wani pursuing M.Sc Chemistry at University of Kashmir, J&K, India and Naveed Bashir Dar, a student of electrical engg. at NIT Srinagar.
Warm regards to Munnazir Bashir also for providing us with refreshing tea while we were compiling ppt.
The postulates of quantum mechanics have been successfully used for deriving exact solutions to Schrodinger equation for problems like A particle in 1 Dimensional box Harmonic oscillator Rigid rotator Hydrogen atom • However for a multielectron system, the SWE cannot be solved exactly due to inter-electronic repulsion terms.
The SWE is solved by method of seperation of variables.
• However, the inter-electronic repulsion term cannot be solved because the variables cannot be seperated and the SWE cannot be solved. • Approximate methods have helped to generate solutions for such and even more complex real quantum systems. • Approximate methods have been developed for solving Schrodinger equation to find wave function and energy of the complex system under consideration. • Two widely used approximate methods are, 1. Perturbation theory 2. Variation method
Perturbation theory is an approximate method that describes a complex quantum system in terms of a simpler system for which the exact solution is known. • Perturbation theory has been categorized into, i. Time independent perturbation theory, proposed by Erwin Schrodinger, where the perturbation Hamiltonian is static. ii. Time dependent perturbation theory, proposed by Paul Dirac, which studies the effect of time dependent perturbation on a time independent Hamiltonian H0.
PERTURBATION THEOREM
FIRST ORDER PERTURBATION THEORY
FIRST ORDER ENERGY CORRECTION
FIRST ORDER WAVE FUNCTION CORRECTION
APPLICATIONS OF PERTURBATION METHOD
SIGNIFICANCE OF PERTURBATION METHOD
This presentation describes about the preparation, properties, bonding modes, classification and applications of metal Dioxygen Complexes. Also explains the MO diagram of molecular oxygen.
NQR - DEFINITION - ELECTRIC FIELD GRADIENT - NUCLEAR QUADRUPOLE MOMENT - NUCLEAR QUADRUPOLE COUPLING CONSTANT - PRINCIPLE OF NQR - ENERGY OF INTERACTION - SELECTION RULE - FREQUENCY OF TRANSITION - APPLICATIONS
GROUP THEORY
CONSTRUCTING CHARACTER TABLE IS FOLLOWED BY 4 STEPS through orthogonality rule
STEP 1 : FIND THE NUMBER OF IRRs
Number of IRs = Number of classes.- In C3v
there is 3 classes so Г1,Г2 Г3
STEP 2: FIND OUT THE DIMENSIONS
Sum of the squares of the dimensions of IRRs = Order of the Group
We have to identify a set of 3 positive integers (I1 I2 I3 dimensions of IRRs) which satisfy this condition
The only value of I which satisfy this condition are 1,1,2 so that I12 = I22
SO 3 IRRs of C3v ,two are 1-D and one is 2-D
STEP 3 : FIND character of two 1-D IRRs
In every point group is 1-D IRR who characters are equal to 1 .this IRRs is called totally symmetric IRR
Thus we have
Which satisfy the rule sum of the square of the characters of all operations in any IRR is equal to the order of the group
FIND characters of another 1-D IRRsConditions
All the characters of this IRRs equal to +1 or -1
Also IRR must be Orthogonal to Г1
Г1 has six +1 as characters of the sym operations 1 for E ; 2 (1) for C3 ; 3 (1) for σv
The characters of Г2 is Orthogonal to Г1 so it has three +1 and three -1
For E in 1-D is +1 ; for 2 C3 in 1-D is +1 ; FOR 3 σV is -1
A ppt compiled by Yaseen Aziz Wani pursuing M.Sc Chemistry at University of Kashmir, J&K, India and Naveed Bashir Dar, a student of electrical engg. at NIT Srinagar.
Warm regards to Munnazir Bashir also for providing us with refreshing tea while we were compiling ppt.
The postulates of quantum mechanics have been successfully used for deriving exact solutions to Schrodinger equation for problems like A particle in 1 Dimensional box Harmonic oscillator Rigid rotator Hydrogen atom • However for a multielectron system, the SWE cannot be solved exactly due to inter-electronic repulsion terms.
The SWE is solved by method of seperation of variables.
• However, the inter-electronic repulsion term cannot be solved because the variables cannot be seperated and the SWE cannot be solved. • Approximate methods have helped to generate solutions for such and even more complex real quantum systems. • Approximate methods have been developed for solving Schrodinger equation to find wave function and energy of the complex system under consideration. • Two widely used approximate methods are, 1. Perturbation theory 2. Variation method
Perturbation theory is an approximate method that describes a complex quantum system in terms of a simpler system for which the exact solution is known. • Perturbation theory has been categorized into, i. Time independent perturbation theory, proposed by Erwin Schrodinger, where the perturbation Hamiltonian is static. ii. Time dependent perturbation theory, proposed by Paul Dirac, which studies the effect of time dependent perturbation on a time independent Hamiltonian H0.
PERTURBATION THEOREM
FIRST ORDER PERTURBATION THEORY
FIRST ORDER ENERGY CORRECTION
FIRST ORDER WAVE FUNCTION CORRECTION
APPLICATIONS OF PERTURBATION METHOD
SIGNIFICANCE OF PERTURBATION METHOD
This presentation describes about the preparation, properties, bonding modes, classification and applications of metal Dioxygen Complexes. Also explains the MO diagram of molecular oxygen.
NQR - DEFINITION - ELECTRIC FIELD GRADIENT - NUCLEAR QUADRUPOLE MOMENT - NUCLEAR QUADRUPOLE COUPLING CONSTANT - PRINCIPLE OF NQR - ENERGY OF INTERACTION - SELECTION RULE - FREQUENCY OF TRANSITION - APPLICATIONS
GROUP THEORY
CONSTRUCTING CHARACTER TABLE IS FOLLOWED BY 4 STEPS through orthogonality rule
STEP 1 : FIND THE NUMBER OF IRRs
Number of IRs = Number of classes.- In C3v
there is 3 classes so Г1,Г2 Г3
STEP 2: FIND OUT THE DIMENSIONS
Sum of the squares of the dimensions of IRRs = Order of the Group
We have to identify a set of 3 positive integers (I1 I2 I3 dimensions of IRRs) which satisfy this condition
The only value of I which satisfy this condition are 1,1,2 so that I12 = I22
SO 3 IRRs of C3v ,two are 1-D and one is 2-D
STEP 3 : FIND character of two 1-D IRRs
In every point group is 1-D IRR who characters are equal to 1 .this IRRs is called totally symmetric IRR
Thus we have
Which satisfy the rule sum of the square of the characters of all operations in any IRR is equal to the order of the group
FIND characters of another 1-D IRRsConditions
All the characters of this IRRs equal to +1 or -1
Also IRR must be Orthogonal to Г1
Г1 has six +1 as characters of the sym operations 1 for E ; 2 (1) for C3 ; 3 (1) for σv
The characters of Г2 is Orthogonal to Г1 so it has three +1 and three -1
For E in 1-D is +1 ; for 2 C3 in 1-D is +1 ; FOR 3 σV is -1
This presentation will be helpful to beginners on chemical aspects of group theory. Also this ppt consists of videos on mirror plane symmetry and rotational axis of symmetry
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APEX INSTITUTE has been established with sincere and positive resolve to do something rewarding for ENGG. / PRE-MEDICAL aspirants. For this the APEX INSTITUTE has been instituted to provide a relentlessly motivating and competitive atmosphere.
1. Linear Algebra for Machine Learning: Linear SystemsCeni Babaoglu, PhD
The seminar series will focus on the mathematical background needed for machine learning. The first set of the seminars will be on "Linear Algebra for Machine Learning". Here are the slides of the first part which is giving a short overview of matrices and discussing linear systems.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
TECHNICAL TRAINING MANUAL GENERAL FAMILIARIZATION COURSEDuvanRamosGarzon1
AIRCRAFT GENERAL
The Single Aisle is the most advanced family aircraft in service today, with fly-by-wire flight controls.
The A318, A319, A320 and A321 are twin-engine subsonic medium range aircraft.
The family offers a choice of engines
Automobile Management System Project Report.pdfKamal Acharya
The proposed project is developed to manage the automobile in the automobile dealer company. The main module in this project is login, automobile management, customer management, sales, complaints and reports. The first module is the login. The automobile showroom owner should login to the project for usage. The username and password are verified and if it is correct, next form opens. If the username and password are not correct, it shows the error message.
When a customer search for a automobile, if the automobile is available, they will be taken to a page that shows the details of the automobile including automobile name, automobile ID, quantity, price etc. “Automobile Management System” is useful for maintaining automobiles, customers effectively and hence helps for establishing good relation between customer and automobile organization. It contains various customized modules for effectively maintaining automobiles and stock information accurately and safely.
When the automobile is sold to the customer, stock will be reduced automatically. When a new purchase is made, stock will be increased automatically. While selecting automobiles for sale, the proposed software will automatically check for total number of available stock of that particular item, if the total stock of that particular item is less than 5, software will notify the user to purchase the particular item.
Also when the user tries to sale items which are not in stock, the system will prompt the user that the stock is not enough. Customers of this system can search for a automobile; can purchase a automobile easily by selecting fast. On the other hand the stock of automobiles can be maintained perfectly by the automobile shop manager overcoming the drawbacks of existing system.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
Student information management system project report ii.pdf
Chapter 03-group-theory (1)
1. Chapter 3 - Group Theory
A Group is a collection of elements which is:
i) closedunder some single-valuedassociative binary
operation
ii) contains a singleelement satisfyingthe identity law
iii) and has a reciprocalelement for each element in the
group
Collection: a specified# of elements (finiteor infinite)
Elements: the consitituentsof the group (i.e., symmetry
operations)
Binary Operation: the combinationof two elements of a
group to yield another element in the group. The
combinationmay be mathematical(addition, subtraction,
etc.) or qualitativeas in the successiveapplicationof two
symmetry operations on an object.
Single-valued: the combinationof two elements yields a
unique result
Closed: the combinationof any two group elements must
always yield another element belonging to the group.
Associative: the associativelaw of combinationmust hold
for the group.
(AB)C = A(BC)
2. Group Theory 2
In general, however, elements of a group do not have to
commute (but they can):
AB ≠ BA
Identity Law: there must be an element in the group which
when combined with any element in the group will leave
them unchanged. This element is calledthe identity or unit
element and it commutes with all elements of the group. It
is given the symbol E.
EA = A AE = A EE = E
Reciprocal Element: for each element A in a group there
must be an element calledthe reciprocal, A1, such that the
followingholds:
AA1 = A1A = E
In general, group multiplicationis not commutative,i.e.,
AB ≠ BA. However, it can be and a group in which
multiplicationis completely commutativeis called an
Abelian Group.
3. Group Theory 3
Group MultiplicationTable (matrix operations)
G3 E A B
E E A B
A A B E
B B E A
Each row and each column in a group multiplicationtable
lists each of the group elements ONCE and ONLY ONCE.
It therefore follows that no two columns or rows may be
identical!
Considera “real” C3 table using symmetry elements:
C3 E C3 C3
2
E E C3 C3
2
C3 C3 C3
2 E
C3
2
C3
2 E C3
(column) × (row)
Abelian group
4. Group Theory 4
Considerthe two different ways we can set up a 4 × 4 table:
G4
1 E A B C
E E A B C
A A E C B
B B C E A
C C B A E
Note that each element times itself generates E.
G4
2 E A B C
E E A B C
A A B C E
B B C E A
C C E A B
Note that this group table aboveis cyclic, that is, the group
is generated by one element:
A = A A3
= C
A2
= B A4
= E
5. Group Theory 5
Note that the G3 (C3) example abovewas also cyclic.
There is only one group combinationpossiblefor the G5
group, which turns out to be cyclic as well:
G5 E A B C D
E E A B C D
A A B C D E
B B C D E A
C C D E A B
D D E A B C
Note the diagonal lining up of the elements in cyclic groups
(symmetry of a matrix sort).
6. Group Theory 6
SubGroups
A subgroup is a self-containedgroup of elements residing
within a larger group.
(integer)
subgroup)of(order
group)mainof(order
k
g
h
G6 E A B C D F
E E A B C D F
A A E D F B C
B B F E D C A
C C D F E A B
D D C A B F E
F F B C A E D
G3 E D F
E E D F
D D F E
F F E D
7. Group Theory 7
Classes
Assume that A and X are elements of a group and we
perform the followingoperation:
X1
AX = B
Where B is anotherelement in the group. B is then called
the similaritytransformof A by X. If this relationship
holds, then A and B are said to be conjugate.
The followingis true for elements that are relatedby
similaritytransforms:
1) Every element is conjugate with itself
A = X1
AX
(X may be equal to the identity element E)
2) If A is conjugate with B, then B is conjugate with A
Thus, if we have:
X1
AX = B
Then there must exist another element Y such that:
Y1
BY = A
3) Finally, if A is conjugate to both B and C, then B and C
must also be conjugate to each other.
A group of elements that are conjugate to one another is
calleda Class of Elements.
8. Group Theory 8
To determine which elements group together to form a
class you have to work out all the similaritytransforms for
each element in the group. Thosesets of elements that
transforminto one another are then in the same class.
Considerthe C3v symmetry point group “matrix”:
C3v E C3 C3
2
v
1 v
2 v
3
E E C3 C3
2
v
1 v
2 v
3
C3 C3 C3
2 E v
2 v
3 v
1
C3
2 C3
2 E C3 v
3 v
1 v
2
v
1 v
1 v
2 v
3 E C3 C3
2
v
2 v
2 v
3 v
1 C3
2 E C3
v
3 v
3 v
1 v
2 C3 C3
2 E
Lets determine the classes of symmetry operationsfor this
point group. Lets start with the similaritytransforms for
the vertical mirror planes:
v
1v
1v
11 = v
1
v
2v
1v
21 = v
3
v
3v
1v
31 = v
2
12. Group Theory 12
If we continuethese similaritytransforms we find that the
varioussymmetry operationsfor C3v break down into the
followingclasses:
E
C3, C3
2
v
1, v
2 , v
3
If we examine the character tables in Cotton we find that
the symmetry operationsare listed and grouped together in
these very same classes:
Corollary: the orders of all the classes must be integral
factors of the order of a group.
Order of a point group = # of symmetry operations
13. Group Theory 13
Matrix Operations
Considerthe followingmatrix:
a11 a12 a13 a14 . . . a1n
a21 a22 a23 a24 . . . a2n
a31 a32 a33 a34 . . . a3n
. . .
an1 an2 an2 an2 . . . amn
Character: sum of diagonal elements
In order to multiply two matrices they must be
conformable,i.e., to multiply matrix A by matrix B, the
number of columns in A must equal the number of rows in
B.
(a11 × b11) + (a12 × b21) = c11
11 12 13 14
21 22 23 24
31 32
11 12 13 14
11 12
21 2
21 22
2
31 32
2 4
3 34
3
3
2
b b b b
b
c c c c
b b b
c c c c
c c c c
a a
a a
a a
3 × 2 2 × 4 = 3 × 4
Row
Column
Row Column
14. Group Theory 14
The symmetry operationscan all be represented
mathematicallyas 3 × 3 square matrices.
To carry out the symmetry operation, you multiply the
symmetry operationmatrix times the coordinatesyou want
to transform. The x, y, z coordinatesare written in vector
format as a 3 × 1 matrix:
x
y
z
For example, the inversionoperationtake the general
coordinatesx, y, z to x, y, z. In matrix terms we
would write:
1 0 0
0 1 0
0 0 1
x
y
z
x
y
z
x(new) = (1)(x) + (0)(y) + (0)(z)
y(new) = (0)(x) + (1)(y) + (0)(z)
z(new) = (0)(x) + (0)(y) + (1)(z)
15. Group Theory 15
Symmetry OperationMatrices:
1 0 0
0 1 0
0 0 1
x
y
z
x
y
z
1 0 0
0 1 0
0 0 1
x x
y y
z z
1 0 0
0 1 0
0 0 1
x
y
z
x
y
z
1 0 0
0 1 0
0 0 1
x
y
zz
x
y
1 0 0
0 1 0
0 0 1
x
y
z
x
y
z
E
i
(xy)
(xz)
(yz)
16. Group Theory 16
cos sin 0
sin cos 0
0 0
'
1
'
x
y
z z
x
y
cos sin 0
sin cos 0
0 0 1
'
'
x
y
x
y
zz
Cn × h = Sn
cos sin 0 1 0 0
sin cos 0 0 1 0
0 0 1 0 0 1
Cn h
Cn
Sn
17. Group Theory 17
Group Representations
The set of four matrices that describe all of the possible
symmetry operations in the C2v point group that can act on
a point with coordinatesx, y, z is calledthe total
representation of the C2v group.
1 0 0 1 0 0 1 0 0 1 0 0
0 1 0 0 1 0 0 1 0 0 1 0
0 0 1 0 0 1 0 0 1 0 0 1
E C2 xz yz
Note that each of these matrices is block diagonalized, i.e.,
the total matrix can be broken up into blocks of smaller
matrices that have no off-diagonal elements between blocks.
These block diagonalizedmatrices can be broken down, or
reduced into simplerone-dimensionalrepresentationsof
the 3-dimensionalmatrix.
If we considersymmetry operations on a point that only has
an x coordinate(e.g., x, 0, 0), then only the first row of our
total representationis required:
C2v E C2 xz yz
1 1 1 1 x
18. Group Theory 18
We can do a similarbreakdownof the y and z coordinates
to setup a table:
C2v E C2 xz yz
1 1 1 1 x
1 1 1 1 y
1 1 1 1 z
These three 1-dimensionalrepresentationsare as simple as
we can get and are called irreduciblerepresentations.
There is one additional irreduciblerepresentationin the
C2v point group. Considera rotation Rz :
The identity operationand the C2 rotation
operationsleavethe directionof the rotation
Rz unchanged. The mirror planes, however,
reverse the directionof the rotation
(clockwiseto counter-clockwise), so the irreducible
representationcan be written as:
C2v E C2 xz yz
1 1 1 1 Rz
4 Classes of symmetry operations =
19. Group Theory 19
4 Irreducible representations!!
Now lets considera case where we have a 2-dimensional
irreduciblerepresentation. Considerthe matrices for C3v
1 0 0 cos120 sin120 0 1 0 0
0 1 0 sin120 cos120 0 0 1 0
0 0 1 0 0 1 0 0 1
E C3 v
In this case the matrices block diagonalizeto give two
reduced matrices. One that is 1-dimensional for the z
coordinate,and the other that is 2-dimensionalrelating the
x and y coordinates.
Multidimensional matrices are represented by their
characters (trace), which is the sum of the diagonal
elements.
Since cos(120º) = 0.50, we can write out the irreducible
representationsfor the 1- (z) and 2-dimensional
“degenerate” x and y representations:
C3v E 2C3 v
1 1 1 z
2 1 0 x,y
20. Group Theory 20
As with the C2v example, we have anotherirreducible
representation(3 symmetry classes = 3 irreducible
representations)based on the Rz rotationaxis. This
generates the full group representationtable:
C3v E 2C3 v
1 1 1 z
2 1 0 x,y
1 1 1 Rz
21. Group Theory 21
Character Tables
Schoenflies symmetry symbol
Mulliken Symbol Notation
1) A or B: 1-dimensional representations
E : 2-dimensional representations
T : 3-dimensional representations
2) A = symmetric with respect to rotationby the Cn axis
B = anti-symmetric w/respect to rotationby Cn axis
Symmetric = + (positive) character
Anti-symmetric = (negative) character
Characters of
the irreducible
representations
Mulliken
symbols
x, y, z
Rx, Ry, Rz
Squares &
binary products
of the
coordinates
22. Group Theory 22
3) Subscripts 1 and 2 associatedwith A and B symbols
indicatewhether a C2 axis to the principleaxis
produces a symmetric (1) or anti-symmetric(2) result.
If C2 axes are absent, then it refers to the effect of
vertical mirror planes (e.g., C3v)
4) Primes and double primes indicaterepresentations
that are symmetric ( ) or anti-symmetric ( ) with
respect to a h mirror plane. They are NOT used
when one has an inversioncenter present (e.g., D2nh or
C2nh).
5) In groups with an inversion center, the subscript“g”
(“gerade” meaning even) represents a Mulliken
symbol that is symmetric with respect to inversion.
23. Group Theory 23
The symbol “u” (“ungerade” meaning uneven)
indicates that it is anti-symmetric.
6) The use of numerical subscripts on E and T symbols
followsome fairly complicatedrules that will not be
discussedhere. Considerthem to be somewhat
arbitrary.
Square and Binary Products
These are higher order “combinations” or products of the
primary x, y, and z axes.
24. Group Theory 24
The Great Orthogonality Theorem
'' ' '
*( ) ( )m m mmn n ni ij
i
nj
j
R R
l l
h
25. Group Theory 25
i (R)mn The element in the mth row and nth column of
the matrix correspondingto the operationR in
the ith irreduciblerepresentationi.
i (R)mn
* complex conjugateused when imaginary or
complex #’s are present (otherwiseignored)
h the order of the group
li the dimension of the ith representation
(A = 1, B = 1, E = 2, T = 3)
delta functions, = 1 when i = j, m = m’, or n =
n’; = 0 otherwise
The different irreduciblerepresentationsmay be thought of
as a series of orthonormal vectors in h-space, where h is the
order of the group.
26. Group Theory 26
Because of the presence of the delta functions, the equation
= 0 unless i = j, m = m’, or n = n’. Therefore, there is only
one case that will play a direct role in our chemical
applications:
0' '( ) ( )
R
nm j m ni R R
0' '( ) ( )
R
nm j m ni R R
( ) ( )
R
i inm nm
i
R R
l
h
if i ≠ j
if m ≠ m’
n ≠ n’
27. Group Theory 27
Five “Rules” about IrreducibleRepresentations:
1) The sum of the squares of the dimensionsof the
irreduciblerepresentationsof a group is equal to the
order, h, of a group.
2
il h
For example, considerthe D3h point group:
l(A1’)2 + l(A2’)2 + l(E’)2 + l(A1”)2 + l(A2”)2 + l(E”)2
(1)2 + (1)2 + (2)2 + (1)2 + (1)2 + (2)2 = 12
2) The sum of the squares of the characters in any
irreduciblerepresentationis also equal to the order of
the group h.
2
( )i
R
R hg
For example, for the E’ representationin D3h:
(E)2 + 2(C3)2 + 3(C2)2 + (h)2 + 2(S3)2 + 3(h)2
h = 12 (order of group)
g = # of symmetry
operations R in a class
Dimensions:
A or B = 1
E = 2
T = 3
28. Group Theory 28
(2)2 + 2(-1)2 + 3(0)2 + (2)2 + 2(-1)2 + 3(0)2 = 12
3) The vectors whose components are the characters of
two different irreduciblerepresentationsare
orthogonal.
0( ) ( )i j
R
g R R
For example, multiply out the A2’ and E’ representations
in D3h:
1(1)(2) + 2(1)(-1) + 3(-1)(0) + 1(1)(2) + 2(1)(-1) + 3(-1)(0)
2 + (-2) + 0 + 2 + (-2) + 0 = 0
4) In a given representationthe characters of all
matrices belonging to operationsin the same class are
identical.
5) The number of irreduciblerepresentationsin a group
is equal to the number of classesin the group.