Transformation of potential energy surfaces for estimating isotopic shifts in anharmonic vibrational frequency calculations.
A transformation of potential energy surfaces (PES) being represented by multi-mode expansions is introduced, which allows for the calculation of anharmonic vibrational spectra of any isotopologue from a single PES. This simplifies the analysis of infrared spectra due to significant CPU-time savings. An investigation of remaining deviations due to truncations and the so-called multi-level approximation is provided. The importance of vibrational-rotational couplings for small molecules is discussed in detail. In addition, an analysis is proposed, which provides information about the quality of the transformation prior to its execution. Benchmark calculations are provided for a set of small molecules.
Institut für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany.
Patrick
P
Meier
Institut für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany.
Dominik
D
Oschetzki
Clemens-Schöpf Institut für Organische Chemie and Biochemie, Technische Universität Darmstadt, Petersenstrasse 22, 64287 Darmstadt, Germany.
Robert
R
Berger
Institut für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany.
Guntram
G
Rauhut