What is optimwidths?

optimwidths is a tool to calculate the Gaussian width parameters used in ab initio multiple spawning (AIMS). It essentially implements a version of the width optimization algorithm for AIMS ¹ first described in the supplementary information of Ref. ² At the moment it only accepts Gaussian16 output files from a force calculation, but in the future more codes will be supported.

Installing and using otpimwidths

The only dependencies of optimwidths are the BLAS and LAPACK libraries, and a Fortran compiler. To compile the code go into the optimwidths folder, change the compiler and library flags in make.vars to the ones you want and type make.

The binary optimwidths.x requires an outputfile generated from a Gaussian16 frequency calculation and an input file input.in that contains the following parameters:

Input variable name	Description	Possible options
nrAtoms	Number of atoms	integer
xtol	Simplex convergence treshold	real
ftol	Function convergence treshold	real
maxiter	Maximum number of iterations	integer
constrained	Constrained optimazation?	logical
prog	Electronic structure program	gaussian
fName	Name of output file	str

Footnotes

1. Thompson, A. L.; Punwong, C.; Martínez, T. J. Chem. Phys. 2010, 370, 70-77 ↩

2. Esch, M. P.; Shu, Y.; Levine, B. G. J. Phys. Chem. A 2019, 123, 13, 2661–2673 ↩