PyVCI: A flexible open-source code for calculating accurate molecular infrared spectra (2016)
AuthorsSibaev, M., Crittenden, D.L.show all
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-negligible VCI matrix elements are stored in sparse matrix format to alleviate the diagonalization problem. CPU and memory requirements may be further controlled by algorithmic choices and/or numerical screening procedures, and recommended values are established by benchmarking using a test set of 44 molecules for which accurate analytical potential energy surfaces are available. Force ﬁelds in normal mode coordinates are obtained from the PyPES library of high quality analytical potential energy surfaces (to 6th order) or by numerical diﬀerentiation of analytic second derivatives generated using the GAMESS quantum chemical program package (to 4th order).
CitationSibaev, M., Crittenden, D.L. (2016) PyVCI: A flexible open-source code for calculating accurate molecular infrared spectra. Computer Physics Communications, (early access online).
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