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VASP
What is VASP?
The Vienna Ab initio Simulation Package (VASP) is a computer program for atomic scale materials modelling, e.g. electronic structure calculations and quantum-mechanical molecular dynamics, from first principles.
VASP computes an approximate solution to the many-body Schrödinger equation, either within density functional theory (DFT), solving the Kohn-Sham equations, or within the Hartree-Fock (HF) approximation, solving the Roothaan equations. Hybrid functionals that mix the Hartree-Fock approach with density functional theory are implemented as well. Furthermore, Green's functions methods (GW quasiparticles, and ACFDT-RPA) and many-body perturbation theory (2nd-order Møller-Plesset) are available in VASP.
In VASP, central quantities, like the one-electron orbitals, the electronic charge density, and the local potential are expressed in plane wave basis sets. The interactions between the electrons and ions are described using norm-conserving or ultrasoft pseudopotentials, or the projector-augmented-wave method.
To determine the electronic groundstate, VASP makes use of efficient iterative matrix diagonalisation techniques, like the residual minimisation method with direct inversion of the iterative subspace (RMM-DIIS) or blocked Davidson algorithms. These are coupled to highly efficient Broyden and Pulay density mixing schemes to speed up the self-consistency cycle.
And what can VASP do?
The following is a (by no means complete) list of VASP features:
Functionals
LDA, GGAs, metaGGAs
Hartree-Fock, Hartree-Fock/DFT hybrids
First derivatives
Forces and stress tensor for DFT, Hartree-Fock, and hybrid functionals
Dynamics and relaxation
Born-Oppenheimer molecular dynamics
Relaxation using conjugate gradient, Quasi-Newton or damped molecular dynamics
Nudged elastic band methods (transition states search)
Climbing dimer method (transition state search)
Magnetism
Collinear and non-collinear
Spin-orbit coupling
Constrained magnetic moments approach
Linear response to electric fields
Static dielectric properties
Born effective charge tensors
Piezoelectric tensors (including ionic contributions)
Linear response to ionic displacements
Phonons
Elastic constants (including ionic contributions)
Internal strain tensors
Optical properties
Frequency dependent dielectric tensors in the independent particle approximation
Frequency dependent tensors in the RPA and TD-DFT
Cassida's equation for TD-DFT and TD-Hartree-Fock
Berry phases
Macroscopic polarization
Finite electric fields
Green's function methods
GW quasiparticles
ACFDT total energies in the RPA
Many-body perturbation theory
2nd-order Møller-Plesset perturbation theory
Gamess
The General Atomic and Molecular Electronic Structure System (GAMESS)
is a general ab initio quantum chemistry package.
GAMESS is a program for ab initio molecular quantum chemistry. Briefly, GAMESS can compute SCF wavefunctions ranging from RHF, ROHF, UHF, GVB, and MCSCF. Correlation corrections to these SCF wavefunctions include Configuration Interaction, second order perturbation Theory, and Coupled-Cluster approaches, as well as the Density Functional Theory approximation. Excited states can be computed by CI, EOM, or TD-DFT procedures. Nuclear gradients are available, for automatic geometry optimization, transition state searches, or reaction path following. Computation of the energy hessian permits prediction of vibrational frequencies, with IR or Raman intensities. Solvent effects may be modeled by the discrete Effective Fragment potentials, or continuum models such as the Polarizable Continuum Model. Numerous relativistic computations are available, including infinite order two component scalar relativity corrections, with various spin-orbit coupling options. The Fragment Molecular Orbital method permits use of many of these sophisticated treatments to be used on very large systems, by dividing the computation into small fragments. Nuclear wavefunctions can also be computed, in VSCF, or with explicit treatment of nuclear orbitals by the NEO code.
A variety of molecular properties, ranging from simple dipole moments to frequency dependent hyperpolarizabilities may be computed. Many basis sets are stored internally, together with effective core potentials or model core potentials, so that essentially the entire periodic table can be considered.
Most computations can be performed using direct techniques, or in parallel on appropriate hardware. Graphics programs, particularly the MacMolplt program (for Macintosh, Windows, or Linux desktops), are available for viewing of the final results, and the Avogadro program can assist with preparation of inputs.
Amber
"Amber" refers to two things: a set of molecular mechanical force fields for the simulation of biomolecules (which are in the public domain, and are used in a variety of simulation programs); and a package of molecular simulation programs which includes source code and demos.
Amber is distributed in two parts: AmberTools15 and Amber14. You can use AmberTools15 without Amber14, but not vice versa. See below for information on how to obtain Amber14.
The Amber14 package builds on AmberTools15 by adding the pmemd program, which resembles the sander (molecular dynamics) code in AmberTools, but provides (much) better performance on multiple CPUs, and dramatic speed improvements on GPUs. In this release, more features from sander have been added to pmemd for both CPU and GPU platforms, including performance improvements, and support for extra points, multi-dimension replica exchange, a Monte Carlo barostat, ScaledMD, Jarzynski sampling, explicit solvent constant pH, GBSA, and hydrogen mass repartitioning. Support is also included for the latest Kepler, Titan and GTX7xx GPUs.
AmberTools consists of several independently developed packages that work well by themselves, and with Amber itself. The suite can also be used to carry out complete molecular dynamics simulations, with either explicit water or generalized Born solvent models. The sander program is now a part of AmberTools.
Allinea
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Leading enterprises and labs that need high performance computing rely on Allinea Forge to help them develop fast, robust software and keep their development teams on track. You'd be in good company with us - users on 70% of the world's largest supercomputers and clusters rely on Allinea Forge.