A new four-dimensional ab initio potential energy surface for N2O-He and vibrational band origin shifts for the N2O-He-N clusters with N=1-40

作者：Wang Lecheng; Xie Daiqian^*; Le Roy Robert J; Roy Pierre Nicholas

来源：Journal of Chemical Physics, 2012, 137(10): 104311.

DOI：10.1063/1.4749248

A new four-dimensional ab initio potential energy surface for N2O-He is constructed at the CCSD(T) level with an aug-cc-pVQZ basis set together with bond functions. The vibrational coordinates Q(1) and Q(3) of N2O are explicitly included, due to the strong coupling between the symmetric and asymmetric stretches of N2O. A global potential energy surface is obtained by fitting the original potential points to a four-dimensional Morse/long range (MLR) analytical form. In the fitting, the ab initio noise in the long range region of the potential is smoothed over by theoretically fixed long range parameters. Two-dimensional intermolecular potentials for both the ground and the excited upsilon(3) states of N2O are then constructed by vibrationally averaging the four-dimensional potential. Based on the two-dimensional potentials, we use the path integral Monte Carlo algorithm to calculate the vibrational band origin shifts for the N2O-HeN clusters using a first order perturbation theory estimate. The calculated shifts agree reasonably well with the experimental values and reproduce the evolution tendency from dimer to large clusters.

• 出版日期2012-9-14
• 单位南京大学