title: Full-Dimensional Potential Energy and Dipole Moment Surfaces of GeH4Molecule and Accurate First-Principle Rotationally Resolved Intensity Predictions in the Infrared.
abstract: Nine-dimensional potential energy surface (PES) and dipole moment surface (DMS) of the germane molecule are constructed using extended ab initio CCSD(T) calculations at 19 882 points. PES analytical representation is determined as an expansion in nonlinear symmetry adapted products of orthogonal and internal coordinates involving 340 parameters up to eighth order. Minor empirical refinement of the equilibrium geometry and of four quadratic parameters of the PES computed at the CCSD(T)/aug-cc-pVQZ-DK level of the theory yielded the accuracy below 1 cm-1for all experimentally known vibrational band centers of five stable isotopologues of70GeH4,72GeH4,73GeH4,74GeH4, and76GeH4up to 8300 cm-1. The optimized equilibrium bond re= 1.517 594 Å is very close to best ab initio values. Rotational energies up to J = 15 are calculated using potential expansion in normal coordinate tensors with maximum errors of 0.004 and 0.0006 cm-1for74GeH4and76GeH4. The DMS analytical representation is determined through an expansion in symmetry-adapted products of internal nonlinear coordinates involving 967 parameters up to the sixth order. Vibration-rotation line intensities of five stable germane isotopologues were calculated from purely ab initio DMS using nuclear motion variational calculations with a full account of the tetrahedral symmetry of the molecules. For the first time a good overall agreement of main absorption features with experimental rotationally resolved Pacific Northwest National Laboratory spectra was achieved in the entire range of 700-5300 cm-1. It was found that very accurate description of state-dependent isotopic shifts is mandatory to correctly describe complex patterns of observed spectra at natural isotopic abundance resulting from the superposition of five stable isotopologues. The data obtained in this work will be made available through the TheoReTS information system.
authors.affiliation: Laboratory of Theoretical Spectroscopy, V. E. Zuev Institute of Atmospheric Optics , SB RAS, 1, Academician Zuev Square, 634021 Tomsk, Russia.
authors.forename: A V
authors.initials: AV
authors.lastname: Nikitin
authors.affiliation: Groupe de Spectrométrie Moléculaire et Atmosphérique, UMR CNRS 7331, Université de Reims, U.F.R. Sciences , B.P. 1039, 51687 Reims Cedex 2, France.
authors.forename: M
authors.initials: M
authors.lastname: Rey
authors.affiliation: Laboratory of Quantum Mechanics of Molecules and Radiative Processes, Tomsk State University , 36 Lenin Avenue, 634050 Tomsk, Russia.
authors.forename: A
authors.initials: A
authors.lastname: Rodina
authors.affiliation: Laboratory of Quantum Mechanics of Molecules and Radiative Processes, Tomsk State University , 36 Lenin Avenue, 634050 Tomsk, Russia.
authors.forename: B M
authors.initials: BM
authors.lastname: Krishna
authors.affiliation: Groupe de Spectrométrie Moléculaire et Atmosphérique, UMR CNRS 7331, Université de Reims, U.F.R. Sciences , B.P. 1039, 51687 Reims Cedex 2, France.
authors.forename: Vl G
authors.initials: VG
authors.lastname: Tyuterev