Artemis, Genome viewer : It loads a genome for viewing. In this demo a local copy of genome is loaded, however Artemis can also load sequences from the Internet.
ClustalX, Sequence alignment : It calls clustalx with a filename as argument. The filename is PPIases, which contains sequence of 10 proteins in FASTA format. To perform sequence alignment from top menu select: Alignment -> Do Complete Alignment. On the pop-up box click on ALIGN.
Ghemical, MD (small molecule): This demo loads sample.mm1gp. To add hydrogens click mouse right button on black area and from the pop-up menu select:Build -> Hydrogens -> Add. To optimize the structure from the pop-menu select: Compute -> Geometry Optimization. Click OK. To perform molecular dynamics: Compute -> Molecular Dynamics.
GROMACS, MD (peptide in water): This demo prepares and performs molecular dynamics for a peptide in water.
Jmol, Quantum chemistry calculation visualization : This demo loads an output file from GAMESS-US run (Hessian calculation for proton between 2 water molecules). Use Extras -> Vibrate to view different normal modes.
Open Babel, Structure file format conversion : This demo converts a protein structure from PDB format to XYZ format using command babel.
NJPlot, Phylogenetic tree creation : This demo create a phylogenetic tree based on a sample input file.
PSI3, Quantum chemistry calculation : This demo runs a quantum chemistry calculation using PSI3 package. The calculation performed is SCF optimization of CH4 with DZP basis set.
PyMOL, Structure visualization and high-quality image rendering : This demo loads a sample project with a protein and 3 conformations of a peptide in the active-site. To change the display use options from S (show), H (hide), L (label) and color menu. To render a high-quality image use ray option in the main menu. To save image use from main menu: File -> Save Image.
Though designed to calculate bonded interactions, GROMACS is extremely fast at calculating non-bonded interactions;
GROMACS provides extremely high performance compared to other programs
GROMACS comes with a large selection of flexible tools for trajectory analysis;
GROMACS is user-friendly, with topologies and parameter files written in clear text format
molecular dynamics (MD) a computer simulation technique where the time evolution of a set of interacting atoms is followed by integrating their equations of motion In molecular dynamics we follow the laws of classical mechanics, and most notably Newton's law: F=ma Here, m is the atom mass, a its acceleration, and F the force acting upon it, due to the interactions with other atoms.
reads in a pdb file and allows the user to chose a forcefield
reads some database files to make special bonds (i.e. Cys-Cys) adds hydrogen's to the protein
generates a coordinate file in Gromacs (Gromos) format (*.gro) and a topology file in Gromacs format (*.top).
converts gromacs files (*.gro) back to pdb files (*.pdb) allows user to setup the box:
the user can define the type of box (i.e. cubic, triclinic, octahedron) set the dimensions of the box edges relative to the molecule (-d 0.7 will set the box edges 0.7 nm from the molecule)center the molecule in the box
molecular dynamics simulation parameters allows the user to set up specific parameters for all the calculations that Gromacs performs.
contains the starting structure of the simulation, the molecular topology file and all the simulation parameters; binary format (all of the above)
em.mdp file :
sets the parameters for running energy minimizations; allows you to specify the integrator (steepest descent or conjugate gradients), the number of iterations, frequency to update the neighbor list, constraints, etc.
md.mdp file :
sets the parameters for running the molecular dynamics program;
solvates the box based on the dimensions specified using editconf
solvates the given protein in the specified solvent (by default SPC- Simple Point Charge water)
water molecules are removed from the box if the distance between any atom of the solute and the solvent is less than the sum of the VanderWaals radii of both atoms (the radii are read from the database vdwradii.dat)
check the total charge. If net charge is not zero, then add counter ions to get neutral system. (select random water molecules and replace with ion). Eg: H2O -> Cl- (remove H1, H2, and rename O as Cl-) or use genion (which does the same thing).
trr: contains the trajectory data for the simulation; binary format.
It contains all the coordinates, velocities, forces and energies as was indicated the mdp file.
xtc: portable format for trajectories which stores the information about the trajectories of the atoms in a compact manner (it only contains cartesian coordinates).
edr: portable file that contains the energies
log: CPU time, MFLOP, etc.
PSI3 is a program system and development platform for ab initio molecular electronic structure computations. The PSI3 suite of quantum chemical programs is designed for efficient, high-accuracy calculations of properties of small to medium-sized molecules. It’s capabilities include a variety of Hartree-Fock, coupled cluster, complete-active-space self-consistent-field, and multi-reference configuration interaction models. Molecular point-group symmetry is utilized throughout to maximize efficiency. Non-standard computations are possible using a customizable input format. PSI3 can perform ab initio computations employing basis sets of up to 32768 contracted Gaussian-type functions of virtually arbitrary orbital quantum number. PSI3 can recognize and exploit the largest Abelian subgroup of the point group describing the full symmetry of the molecule.
It includes mature programming interfaces for parsing user input, accessing commonly used data such as basis-set information or molecular orbital coefficients, and retrieving and storing binary data especially multi-index quantities such as electron repulsion integrals. This platform is useful for the rapid implementation of both standard quantum chemical methods, as well as the development of new models. Features that have already been implemented include Hartree-Fock, multiconfigurational self-consistent-field, second-order Møller-Plesset perturbation theory, coupled cluster, and configuration interaction wave functions. Distinctive capabilities include the ability to employ Gaussian basis functions with arbitrary angular momentum levels; linear R12 second-order perturbation theory; coupled cluster frequency-dependent response properties, including dipole polarizabilities and optical rotation; and diagonal Born-Oppenheimer corrections with correlated wave functions.