Kim, Gapsue (1997) Ab initio calculation of the excited states of some diatomic molecular ions. PhD thesis, University of Warwick.

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Abstract

This thesis aims to provide theoretical information by using ab initio calculations as a
bridge between theory and experiment. This thesis presents calculations of potential
energy curves for the diatomic molecular ions NF+, PCl+, AsCl+ and BBr+ and
preliminary potential energy surfaces for HC + NO.
For the diatomic molecular ions, this work presents the low-lying electronic states of
NF+, PCl+, AsCl+ and BBr+ correlating with the lowest dissociation asymptotes, namely
N+(3p) + F(2p), P+(3P) + Cl(2p),
As+(3p) + Cl(2p),
B+(1S) + Br(2P) and B(2p) + Br+(3p).
In this work CASSCF and CI calculations have been performed with the correlation-consistent
valence quadruple-zeta (VQZ) basis sets for NF+ and PCl+, averaged atomic
natural orbital (ANO) basis sets for AsCl+ and BBr+, and the correlation-consistent
valence double-zeta (VDZ) basis sets for HC + NO. From the calculations of
potential energy curves four bound states, namely X2Π, A2Π, 14Σ and 14Π, are found
for NF+, PCl+ and AsCl+, and there are many more bound states, namely 12Σ+, 12Π, 22Π, 22Σ+, 12Δ, 12Σ-, 4Σ+, 4Δ, and 14Σ-, for BBr+. For all the bound states
spectroscopic constants have been calculated. For NF+, PCl+ and AsCl+ our results
are in good agreement with the available spectroscopic data. However, for BBr+ the
theoretical values are in disagreement with experimental data. It is suggested that a
reinvestigation of the experimental spectrum of this species would be worthwhile.
Calculations of transition moments for bound-bound transitions have been carried out.
For HC + NO the linear structures for 1Σ+, 1Σ-, 3Σ+ and 3Σ- states and the bent structure
for 1A' state have been calculated. These calculations were intended to obtain
potential energy surfaces for the reaction of HC with NO. However, due to the lack
of time left, only preliminary calculations are completed. Reaction without an
activation barrier may occur for a non-collinear approach of HC to NO.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QD Chemistry
Library of Congress Subject Headings (LCSH):	Quantum chemistry, Ions
Official Date:	1997
Dates:	Date Event 1997 Submitted
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Hirst, David M. (David Michael)
Extent:	[xvii], 307 p.
Language:	eng

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