MULTIMODE calculations of the infrared spectra of H 7 + and D 7 + using ab initio potential energy and dipole moment surfaces
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We present a new ab initio potential energy surface (PES) and a dipole moment surface (DMS) for H 7 + in the bound region. The PES is a linear least-squares fit to 42,525 ab initio points whose energies were computed with CCSD(T)-F12b/cc-pVQZ-F12 theory, and the DMS is a fit to dipole moments calculated at MP2 level of theory. The PES and DMS describe the bound region of H 7 + precisely. MULTIMODE (MM) calculations of the infrared spectra of H 7 + and D 7 + were performed using the new PES and DMS. These calculations were carried out at the lowest three stationary points using the single-reference version of MM, and only the five high-frequency modes were considered. The calculated spectra agree well with the recent experimental predissociation action spectra.
KeywordsH7+ Ab initio potential energy surface Large-amplitude motion MULTIMODE Infrared spectrum
C.Q. and J.M.B. thank NASA for financial support through Grant No. 370NNX12AF42G from the NASA Astrophysics Research and Analysis program. R.P. thanks the Centro de Calculo (IFF-CSIC) and SGAI (CSIC) for allocation of computer time. Supports from MICINN, Spain, Grant No. FIS2011-29596-C02-01, Consolider-Ingenio 2010 Programme CSD2009-00038 (MICINN), and COST Action CM1002 (CODECS) are gratefully acknowledged by R.P. We thank Mike Duncan for sending his experimental spectra.
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