Molecular potentials and relaxation dynamics

Conference · Mon May 18 04:00:00 EDT 1981

OSTI ID:6405617

Karo, A M

The use of empirical pseudopotentials, in evaluating interatomic potentials, provides an inexpensive and convenient method for obtaining highly accurate potential curves and permits the modeling of core-valence correlation, and the inclusion of relativistic effects when these are significant. Recent calculations of the X/sup 1/..sigma../sup +/ and a/sup 3/..sigma../sup +/ states of LiH, NaH, KH, RbH, and CsH and the X/sup 2/..sigma../sup +/ states of their anions are discussed. Pseudopotentials, including core polarization terms, have been used to replace the core electrons, and this has been coupled with the development of compact, higly-optimized basis sets for the corresponding one- and two-electron atoms. Comparisons of the neutral potential curves with experiment and other ab initio calculations show good agreement (within 1000 cm/sup -1/ over most of the potential curves) with the difference curves being considerably more accurate. In the method of computer molecular dynamics, the force acting on each particle is the resultant of all interactions with other atoms in the neighborhood and is obtained as the derivative of an effective many-body potential. Exploiting the pseudopotential approach, in obtaining the appropriate potentials may be very fruitful in the future. In the molecular dynamics example considered here, the conventional sum-of-pairwise-interatomic-potentials (SPP) approximation is used with the potentials derived either from experimental spectroscopic data or from Hartree-Fock calculations. The problem is the collisional de-excitation of vibrationally excited molecular hydrogen at an Fe surface. The calculations have been carried out for an initial vibrotational state v = 8, J = 1 and a translational temperature corresponding to a gas temperature of 500/sup 0/K. Different angles of approach and different initial random impact points on the surface have been selected. For any given collision with the wall, the molecule may pick up or lose vibrotatonal and translational energy.

• Research Organization: Lawrence Livermore National Lab., CA (USA)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6405617
• Report Number(s): UCRL-85577(Rev.1); CONF-810442-2(Rev.1)
• Country of Publication: United States
• Language: English

Related Subjects

640305* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Theory-- (-1987)
74 ATOMIC AND MOLECULAR PHYSICS
ALKALI METAL COMPOUNDS
CESIUM COMPOUNDS
CESIUM HYDRIDES
COLLISIONS
DATA
ENERGY LEVELS
EXCITED STATES
HARTREE-FOCK METHOD
HYDRIDES
HYDROGEN COMPOUNDS
INFORMATION
INTERATOMIC FORCES
LITHIUM COMPOUNDS
LITHIUM HYDRIDES
MOLECULE COLLISIONS
MOLECULE-MOLECULE COLLISIONS
MOLECULES
NUMERICAL DATA
POTASSIUM COMPOUNDS
POTASSIUM HYDRIDES
ROTATIONAL STATES
RUBIDIUM COMPOUNDS
RUBIDIUM HYDRIDES
SODIUM COMPOUNDS
SODIUM HYDRIDES
THEORETICAL DATA
VIBRATIONAL STATES