Electronic structure of the ground and excited states of Mg/sup +//sub 2/ and Mg/sub 2/

Journal Article · Thu Sep 01 04:00:00 EDT 1977 · J. Chem. Phys.; (United States)

OSTI ID:7319359

Stevens, W J; Krauss, M

The ground and excited valence states of Mg/sup +//sub 2/ and Mg/sub 2/ are calculated using the multiconfiguration self-consistent-field method. The energy curves of the X /sup 1/..sigma../sup +//sub g/, /sup 3/PI/sub g/, /sup 3/..sigma../sup +//sub u/, /sup 3/PI/sub u/, /sup 3/..sigma../sup +//sub g/, /sup 1/PI/sub g/, /sup 1/..sigma../sub u//sup +/, /sup 1/PI/sub u/, and 2 /sup 1/..sigma../sup +//sub g/..mu.. states of Mg/sub 2/ and the /sup 2/..sigma../sup +//sub u/ and /sup 2/PI/sub ..mu../ curves of Mg/sup +//sub 2/ are obtained for internuclear separations between 4 and 15 bohr. All of the excited states except the /sup 3/PI/sub u/ and /sup 3/..sigma../sup +//sub g/ are found to be bound while the ground state is a weakly bound van der Waals molecule. Comparison between the calculated and experimentally known X /sup 1/..sigma../sup +//sub g/ and /sup 1/..sigma../sup +//sub u/ energy curves shows good agreement for the equilibrium internuclear separation, but the calculated D/sub e/ (620 cm/sup -1/) for the best approximation of the X /sup 1/..sigma../sup +//sub g/ state exceeds the experimental value by about 40%, and the calculated D/sub e/ for the /sup 1/..sigma../sup +//sub u/ state is smaller than the experimental value of 9387 cm/sup -1/ by about 1800 cm/sup -1/. Analysis of the electronic structure of the excimers shows that the triplet states and the /sup 1/PI/sub g/ state are qualitatively described by covalent molecular orbital theory, but all of the other bound singlets require more complicated descriptions including covalent configurational mixing, charge transfer, and Rydberg--covalent configuration mixing. Only the /sup 1/PI/sub u/ state can be unambiguously characterized as a charge transfer state. The Mg/sub 2/ states were calculated to provide a model of the Group II excimer systems, which are candidates for the active media of lasers.

• Research Organization: Time and Frequency Division, National Bureau of Standards, Boulder, Colorado 80302
• OSTI ID: 7319359
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 67:5; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
ALKALINE EARTH METALS
ATOMIC IONS
CHARGED PARTICLES
ELECTRONIC STRUCTURE
ELEMENTS
ENERGY LEVELS
EXCITED STATES
GROUND STATES
IONS
MAGNESIUM
MAGNESIUM IONS
METALS
MOLECULAR IONS
MOLECULES
SELF-CONSISTENT FIELD