THE ELECTRONIC STRUCTURE OF LiH AND Li$sub 2$ AND THE QUADRUPOLE MOMENT OF Li$sup 7$

Journal Article · Sun Oct 01 04:00:00 EDT 1961 · Dissertation Abstr.

OSTI ID:4802585

Kahalas, S L

Hartree-Fock self-consistent-field calculations of the Roothaan (linear combination of atomic orbitals-molecular orbital) type are carried out on an electronic computer for LiH and Li/sub 2/ using an extended-basis set of Slater- type atomic orbitals (i.e., by the so-called SCFLCAO-MO-STO method). Configuration-interaction calculations on LiH result in a total molecular energy of 99.34% of the experimental value, and a dissociation energy of 89.33% of the experimental value. Similar calculations in Li/sub 2/ result in 99.40% and 89.9% respectively for these two numbers. The enengy of atomic Li, which enters the dissociation-energy calculation, is calculated to an accuracy of 99.42%. The electric field gradient is calculated (with configuration interaction) in LiH and Li/sub 2/. With the measured LiH quadrupole coupling constant, the quadrupole moment of Li/sup 7/ is found to be-3.56 x 10/sup -26/ cm/sup 2/. With the measured Li/sub 2/ quadrupole coupling constant, the quadrupole moment of Li/sup 7/ is found to be-4.5 x 10/sup -26/ cm/sup 2/. The best estimate for the magnitude is (4.0 plus or minus 0.5) x 10/sup -26/ cm/sup 2/; the sign is unambiguously determined to be negative, in agreement with theoretical predictions from nuclear models. The electric field gradient in Li/sub 2/ is found to be a sensitive function of internuclear distance. The dipole moment of LiH is calculated to be-5.83 Debyes and the quadrupole coupling constant of deuterium in LiD to be + 39.24 kc. Large contributions in configuration interaction occur from p pi orbitals for LiH and Li/sub 2/ and from p orbitals for Li. No Sternheimer correction need be included in the calculation of the electric field gradient, when a Hartree-Fock wave function is used for a closedshell atom or molecule. It is found that calculations for LiH and Li/sub 2/ by the SCF-LCAO-MO-STO method, used in conjunction with a large set of basis orbitals and configuration interaction, can yield results of sufficient accuracy that confidence may be placed in the theoretical description of molecular properties by this method.

• Research Organization: Boston Univ.
• NSA Number: NSA-16-027778
• OSTI ID: 4802585
• Journal Information: Dissertation Abstr., Journal Name: Dissertation Abstr. Vol. Vol: 22
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ATOMIC MODELS
COMPUTERS
CONFIGURATION
DEUTERIUM COMPOUNDS
DIPOLES
ELECTRIC FIELDS
ELECTRIC MOMENTS
ELECTRONS
INTERACTIONS
LITHIUM
LITHIUM 7
LITHIUM HYDRIDES
MAGNETIC MOMENTS
NUMERICALS
PHYSICS
SPECTRA