PyVCI: A flexible open-source code for calculating accurate molecular infrared spectra

This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2018) Abstract The PyVCI program package is a general purpose open-source code for simulating accurate molecular spectra, based upon force field expansions of the potential energy surface in normal mode coordinates. It includes harmonic normal coordinate analysis and vibrational configuration interaction (VCI) algorithms, implemented primarily in Python for accessibility but with time-consuming routines written in C. Coriolis coupling terms may be optionally included in the vibrational Hamiltonian. Non-negl... Title of program: PyVCI Catalogue Id: AFAC_v1_0 Nature of problem The simulation of accurate molecular vibrational spectra is a significant and long-standing problem in computational chemistry. There are two major challenges: constructing an accurate ab initio potential energy surface and solving the nuclear vibrational problem. Both scale poorly with respect to molecular size, requiring large amounts of CPU time and memory. Versions of this program held in the CPC repository in Mendeley Data AFAC_v1_0; PyVCI; 10.1016/j.cpc.2016.02.02