An accurate global potential energy surface, dipole moment surface, and rovibrational frequencies for NH(3)
Xinchuan Huang1, David W Schwenke, Timothy J Lee
1NASA Ames Research Center, Moffett Field, California 94035-1000, USA. xinchuan.huang-1@nasa.gov
Abstract:
A global potential energy surface (PES) that includes short and long range terms has been determined for the NH(3) molecule. The singles and doubles coupled-cluster method that includes a perturbational estimate of connected triple excitations and the internally contracted averaged coupled-pair functional electronic structure methods have been used in conjunction with very large correlation-consistent basis sets, including diffuse functions. Extrapolation to the one-particle basis set limit was performed and core correlation and scalar relativistic contributions were included directly, while the diagonal Born-Oppenheimer correction was added. Our best purely ab initio PES, denoted "mixed," is constructed from two PESs which differ in whether the ic-ACPF higher-order correlation correction was added or not. Rovibrational transition energies computed from the mixed PES agree well with experiment and the best previous theoretical studies, but most importantly the quality does not deteriorate even up to 10 300 cm(-1) above the zero-point energy (ZPE). The mixed PES was improved further by empirical refinement using the most reliable J=0-2 rovibrational transitions in the HITRAN 2004 database. Agreement between high-resolution experiment and rovibrational transition energies computed from our refined PES for J=0-6 is excellent. Indeed, the root mean square (rms) error for 13 HITRAN 2004 bands for J=0-2 is 0.023 cm(-1) and that for each band is always
More Related Videos
Related Concept Videos
NMR Spectroscopy Of Amines
IR Spectrum Peak Splitting: Symmetric vs Asymmetric Vibrations
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
Hybridization of Atomic Orbitals I
IR Frequency Region: X–H Stretching
VSEPR Theory and the Effect of Lone Pairs


