Mark L. Olson

The molecular electronic structure of the lowest 1Σ+g, 3Σ+u, 1Σ+u, 3Σ+g, 1Πu, 1Πg, 3Πu, and 3Πg states of Na2

The multiconfiguration self‐consistent field wave functions and potential energy curves for the lowest lying 1Σ+g, 1Σ+u, 3Σ+g, 3Σ+u, 1Πg, 1Πu, 3Πg, and 3Πu states of Na2 are reported. We find good agreement with recent experimental estimates of the dissociation energies for the 1Σ+g and 1Σ+u states. We find the long range hump in the B 1Πu curve to have its maximum height of 520 cm−1 above the separated atom asymptote at R=6.45±0.1 A; recent experimental estimates of the height are 474 and 554±120 cm−1.

The electronic structure and spectra of the X 1Σ+g and A 1Σ+u states of Li2

The potential energy curves for the X 1Σ+g and the A 1Σ+u states of Li2 have been calculated on the single configuration Hartree–Fock–Roothaan (HF) level, and on the multiconfiguration self‐consistent‐field (MCSCF) level. The MCSCF results give binding energies De (X 1Σ+g) =8297 cm−1 and De (A 1Σ+u) =9299 cm−1; a semiempirical scaling which reproduces the experimental vibrational energy level spacings suggests ’’most‐likely’’ dissociation energies De′ (X 1Σ+g=8450±100 cm−1 and De′ (A  (1Σ+u) =9400±100 cm−1.

Accurate potential energy curves for the 3Σ+u and b3Σ+g states of Li2

Abstract Accurate multi-configuration SCF calculations of the potential energy curves for the 3 Σ + u and b 3 Σ + g states of Li 2 are presented. The experimental detection of these states is discussed. The implications of the crossing of the a 3 Π u state potential with the 3 Σ + u potential for a poposed Li 2 laser is discussed.

The lowest 1Πg, 3Πg, 1Πu and 3Πu states of Li2

Abstract The potential energy curves for the lowest 1 Π g , 3 Π g , 1 Π u and 3 Π u states of Li 2 have been calculated on the single configuration Hartree—Fock—Roothaan, (HF), level and on the multiconfiguration SCF level by using between two and four configurations for each state. We present an improved MC SCF potential curve for the B 1 Π u state and present for the first time MC SCF potential curves for the 1 Π g 3 Π g and 3 Π u states. We show the 1 Π g and 3 Π u states to be bound and the 3 Π g state to be unbound with respect to separated HF atoms. The shapes of the potentials of these states are discussed in terms of avoided crossings of Hartree—Fock curves and in terms of the dispersion interactions at long range which are dominated by the C 3 R −3 term. A detailed comparison with the long-range behavior of the corresponding states of H 2 helps to understand the substantially different appearance of the potential curves for these isovalent molecules. For the Li 2 Π states we present an improved value of C 3 = ±5.6594 ± 0.0010 au (the 1 Π u and 3 Π g states have the positive sign).

The potential energy curve for the B1IIu state of Li2

Abstract Multiconfiguration self-consistent field calculations of the potential curve for the B 1 Π u state of Li 2 show a 700 cm −1 high hump at 5.365 A in good agreement with experimental estimates of 930 ± 300 cm −1 and 523 ± 50 cm −1 .

The vibrational energy levels of the A 1Σ+u state of Li2

The Kusch–Hessel assignment of Dunham constants Yi,O for the A 1Σ+u state of Li2 are corroborated by the theoretical vibrational energy eigenvalues we base on our accurate multiconfiguration self‐consistent field (MCSCF) calculations. The MCSCF potential curve suggests that dissociation occurs at v′=118 at an energy De=9299 cm−1; a semiempirical scaling of this result gives our best estimate of D′e=9400 cm−1.