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Theoretical study of the unusual potential energy curve of the A (1)Sigma(+) state of AgH

Witek, HA; Fedorov, DG; Hirao, K; Viel, A and Widmark, Per-Olof LU (2002) In Journal of Chemical Physics 116(19). p.8396-8406
Abstract
The A (1)Sigma(+) potential energy curve of AgH is studied by means of the second-order multistate multireference perturbation theory including the spin-orbit and relativistic effects. The anomalous behavior of the vibrational energy levels observed in experiment is reproduced well by theory. An analysis of the A (1)Sigma(+) wave function shows that at the internuclear distance of 4-6 Angstrom, a partial electron transfer from the 5p(z) orbital of silver to the 1s orbital of hydrogen occurs. This admixture of the ionic-like [core] 4d(10)1s(H)(2) configuration occurring in A (1)Sigma(+) due to two avoided crossings, namely X (1)Sigma(+) with A (1)Sigma(+) and A (1)Sigma(+) with C (1)Sigma(+), is found to be responsible for the unusual shape... (More)
The A (1)Sigma(+) potential energy curve of AgH is studied by means of the second-order multistate multireference perturbation theory including the spin-orbit and relativistic effects. The anomalous behavior of the vibrational energy levels observed in experiment is reproduced well by theory. An analysis of the A (1)Sigma(+) wave function shows that at the internuclear distance of 4-6 Angstrom, a partial electron transfer from the 5p(z) orbital of silver to the 1s orbital of hydrogen occurs. This admixture of the ionic-like [core] 4d(10)1s(H)(2) configuration occurring in A (1)Sigma(+) due to two avoided crossings, namely X (1)Sigma(+) with A (1)Sigma(+) and A (1)Sigma(+) with C (1)Sigma(+), is found to be responsible for the unusual shape of the A (1)Sigma(+) potential energy curve: the effective potential is a superposition of a Morse-like covalent interaction between Ag and H, and the electrostatic ionic-like interaction between Ag+ and H-. We present spectroscopic parameters, vibrational levels, and rotational constants computed for a large number of vibrational levels and observe good agreement with available experimental data. The equilibrium distance agrees within 0.01 Angstrom and the vibrational frequency within 60 cm(-1) for the state-specific calculations. Larger relative discrepancy is observed for omega(e)x(e), about 30 cm(-1), however the non-Morse-like nature of the energy curve makes it impossible to describe the levels only with omega and omega(e)x(e), so that direct comparison is not well defined. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Chemical Physics
volume
116
issue
19
pages
8396 - 8406
publisher
American Institute of Physics
external identifiers
  • wos:000175297600018
  • scopus:0037088381
ISSN
0021-9606
DOI
10.1063/1.1465403
language
English
LU publication?
yes
id
c1e9e577-86d8-4918-a047-e03137e06911 (old id 339562)
date added to LUP
2007-11-09 16:01:55
date last changed
2017-01-01 04:43:21
@article{c1e9e577-86d8-4918-a047-e03137e06911,
  abstract     = {The A (1)Sigma(+) potential energy curve of AgH is studied by means of the second-order multistate multireference perturbation theory including the spin-orbit and relativistic effects. The anomalous behavior of the vibrational energy levels observed in experiment is reproduced well by theory. An analysis of the A (1)Sigma(+) wave function shows that at the internuclear distance of 4-6 Angstrom, a partial electron transfer from the 5p(z) orbital of silver to the 1s orbital of hydrogen occurs. This admixture of the ionic-like [core] 4d(10)1s(H)(2) configuration occurring in A (1)Sigma(+) due to two avoided crossings, namely X (1)Sigma(+) with A (1)Sigma(+) and A (1)Sigma(+) with C (1)Sigma(+), is found to be responsible for the unusual shape of the A (1)Sigma(+) potential energy curve: the effective potential is a superposition of a Morse-like covalent interaction between Ag and H, and the electrostatic ionic-like interaction between Ag+ and H-. We present spectroscopic parameters, vibrational levels, and rotational constants computed for a large number of vibrational levels and observe good agreement with available experimental data. The equilibrium distance agrees within 0.01 Angstrom and the vibrational frequency within 60 cm(-1) for the state-specific calculations. Larger relative discrepancy is observed for omega(e)x(e), about 30 cm(-1), however the non-Morse-like nature of the energy curve makes it impossible to describe the levels only with omega and omega(e)x(e), so that direct comparison is not well defined.},
  author       = {Witek, HA and Fedorov, DG and Hirao, K and Viel, A and Widmark, Per-Olof},
  issn         = {0021-9606},
  language     = {eng},
  number       = {19},
  pages        = {8396--8406},
  publisher    = {American Institute of Physics},
  series       = {Journal of Chemical Physics},
  title        = {Theoretical study of the unusual potential energy curve of the A (1)Sigma(+) state of AgH},
  url          = {http://dx.doi.org/10.1063/1.1465403},
  volume       = {116},
  year         = {2002},
}