# Heuristic computation of the rovibrational G matrix in optimized molecule-fixed axes. Gmat 2.1

## Description

Abstract Gmat 2.1 is a program able to compute the rovibrational G matrix in different molecule-fixed axes extending the capabilities of Gmat 1.0. The present version is able to select optimal molecule-fixed axes minimizing the pure rotational kinetic elements, the rovibrational kinetic elements or both simultaneously. To such an end, it uses a hybrid minimization approach. Thus, it combines a global search heuristic based in simulated annealing with a gradient-free local minimization. As the previous... Title of program: Gmat 2.1 Catalogue Id: AECZ_v2_0 Nature of problem When building molecular rovibrational Hamiltonians, the kinetic terms depend on the molecule-fixed axes orientation. Thus, an appropriate orientation can significantly simplify the treatment of pure rotation and rovibrational coupling. The kinetic terms are collected in the rovibrational G matrix. Thus, selection of an appropriate molecule-fixed reference frame is equivalent to localize the axes that minimize specific G matrix elements. From this standpoint, three different kinds of molecule-fix ... Versions of this program held in the CPC repository in Mendeley Data AECZ_v1_0; Gmat; 10.1016/j.cpc.2009.01.006 AECZ_v2_0; Gmat 2.1; 10.1016/j.cpc.2010.04.016 This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2019)