ANT 08
A Molecular Dynamics Program for Performing
Classical and Semiclassical Trajectory Simulations for Electronically Adiabatic
and Nonadiabatic Processes for Gas Phase and Materials Systems
Zhen Hua Li, Ahren W. Jasper, David A. Bonhommeau, Rosendo Valero, and Donald G. Truhlar
Department of Chemistry and Supercomputing
Most recent version: 08
Date of most recent version: July 23, 2008
Date of most recent manual update: July 23, 2008
ANT is a molecular dynamics program written in FORTRAN 77 for calculating "Adiabatic and Nonadiabatic Trajectories." It can handle both reactive trajectories and unimolecular processes. It can be run at fixed energy or for thermal ensembles. For an electronically adiabatic process, the user must supply a potential energy surface, and for a nonadiabatic process the user must supply two or more diabatic surfaces and their diabatic couplings. Electronically nonadiabatic processes can be treated in either the adiabatic or diabatic representation by a variety of methods including surface hopping by the fewest switches with time uncertainty (FSTU) algorithm or the FSTU with stochastic decoherence (FSTU/SD) method, and the density matrix propagation by the coherent switches with decay of mixing (CSDM) algorithm. Several methods to ensure zero-point energy maintenance in classical trajectory simulations are also available (TRAPZ-like methods). The current version of ANT has 36 test runs, corresponding to various calculations on unimolecular or photochemical processes of Al2, Al3, Al13, Al20, HBr, and NH3 and bimolecular collisions of Al with Al2, Al2 with Al2, Al with Al59, OH with H2, Li with HF, M with CH, and Y with RH, where M, Y, and R are model atoms.
One can run ensembles of classical trajectories (also called molecular dynamics) on a single user-supplied potential energy surface or on coupled surfaces; the latter is called electronically nonadiabatic dynamics or non-Born-Oppenheimer dynamics. Several non-Born-Oppenheimer (multi-surface) trajectory methods are available, including:
Thermal ensembles may be controlled by various thermostats (Berendsen, Anderson, or two-chain Nosé-Hoover) and/or a Berendsen barostat.
There are options for geometry optimization, normal mode analysis, and simulated annealing.
For single-surface dynamics, the user must supply a subroutine that calculates the potential energy surface and its gradient.
For multi-surface dynamics, the user must supply a subroutine that calculates the coupled diabatic potential energy surfaces, their scalar couplings, and the gradients of the surfaces and couplings. However the coupled-surface dynamics may be carried out in either the diabatic or adiabatic representation; in the latter case the program calculates the adiabatic surfaces and their coupling vector due to nuclear momentum by starting with the diabatic information in the user-supplied subroutine. This option is available for an arbitrary number of states.
Sample potential energy surface routines, including gradients, are available in the POTLIB library.
The ANT code has been tested successfully on the following platforms:
Computer
OS
Compiler
IBM SP Power3
AIX 5.1
xlf
IBM Regatta Power4
AIX 5.2
xlf
SGI Altix
SuSE
Intel FORTRAN compiler 8.1
Intel PC cluster
Redhat Enterprise Linux 3 / Fedora Core 3
G77
We are distributing ANT. If you wish to obtain the program please print, fill out, and sign the license below and fax to Donald G. Truhlar at 612-626-9390.
Hondoplus Home Page
Don Truhlar's
Home Page
Computational Chemistry at the University
of Minnesota
Minnesota Supercomputing Institute
Department of Chemistry at the University
of Minnesota
Updated: Jul 23, 2008 by Hannah Leverentz and David Bonhommeau