Quantum study of the H3 system

Author: Peng, Zhengwei

Year: 1991

Degree: Dissertation (Ph.D.)

Advisor: Kuppermann, Aron

Committee Member: Unknown, Unknown

Option: Physics

DOI: 10.7907/6h1q-ve21

Abstract

In this thesis, an ab initio quantum; study of both electronic and nuclear motions of the H3 system is presented. Results of the ab initio calculations for the lowest four electronic potential energy surfaces of the H3 system are given, as well as for the electric dipole transition moments between them. The calculated Rydberg spectra compare well with previous calculations and with known experimental results. The ground state and the third excited state surfaces have been fitted using the rotated Morse cubic spline (RMCS) method. The ro-vibrational eigenstates of H3 on the upper sheet of the Double Many Body Expansion (DMBE) surface were calculated using a variational method and a new hyperspherical coordinate propagation method. The full P3 nuclear permutation symmetry and the molecular Aharonov-Bohm (MAB) (or geometric phase) effect were included in the hyperspherical coordinate propagation method. The MAB effect has a profound influence on the bound ro-vibrational states of the H3 system. The ro-vibrational bound states of H3 in the third excited 2pz 2A"2 electronic state were also studied. The Rydberg nature of this electronic state leads to ro-vibrational nuclear motion similar to that of the H+3 ion. The comparison between the calculated values of the ro-vibrational constants and the corresponding experimental results suggests that the 2pz 2A"2 RMCS surface still needs some improvement.

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