Extraction of analytical potential function parameters from ab initio potential energy surfaces and analytical forces. J.M. Hayes, J.C. Greer.

PROGRAM SUMMARY
Title of program: PAROPT
Catalogue identifier: ADQD
Ref. in CPC: 147(2002)803
Distribution format: tar gzip file
Operating system: UNIX (HP-UX, Solaris, AIX)/LINUX
High speed store required: 32MK words
Number of bits in a word: 32
Number of lines in distributed program, including test data, etc: 4832
Keywords: Molecular mechanics, Forcefields, Atomistic simulation, Parameter extraction, Structure.
Programming language used: Fortran
Computer: HP workstation , Sun workstation , IBM workstation , Pentium-PC .

Nature of physical problem:
PAROPT is a program for the representing molecular interactions by the extraction of forcefield parameters. This allows analytical modelling based upon ab initio data, validation of the forcefields against known experimental data, and for use in subsequent molecular mechanics, Monte Carlo, and molecular dynamics simulations.

Method of solution:
The method of Metropolis simulated annealing is applied to the multi-variate optimization problem required to determine a forcefield parameter set. The program offers the possibility of fitting energies, forces or a combination of forces and energies. Analytical calculation of forces is used within the program.

Restrictions:
The program is limited by the maximum number of parameters that may be simultaneously optimized within a Metropolis simulated annealing scheme. The specific number of parameters for an optimization run is case dependent.

Typical running time:
A few seconds on a Sun Sparc Ultra 80.