The time dependent Hartree-Fock calculation of ion-molecule scattering

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:6054270

Tiszauer, D H

An alternative semiclassical method of handling reactive molecular collisions that involve charge exchange or electronic transition is presented. A means of time propagating the electronic wave function and time propagating the classical equations of motion for the nuclei through the collision in a self-consistent fashion is developed by use of the time-dependent Hartree Fock (TDHF) method. This replaces the traditional semiclassical two-step approach which requires a calculation of the electronic potential energy surfaces and then solves for the classical nuclear motion on these surfaces. It is shown that the self-consistent propagation of the electronic wave function and the classical nuclear motion implicitly includes the nuclei-electronic coupling that is normally ignored in the Born-Oppenheimer approximation. The coupling included is responsible for nonadiabatic electronic transitions encountered in molecular collisions. The TDHF method is tested on a model collision of H{sub 2}+H{sup +} in the low energy (2 eV) regime. The program used in the computations was adapted from previous nuclear and atomic TDHF calculations, and was implemented on a vector machine. Results of the calculation qualitatively compare to the known results for the H{sub 2}+H{sup +} reactive system showing reaction, electronic transition, and translational to vibrational energy transfer. Developments in computational single-processor speed, the greater availability of vector and array processors, and the simplicity of graphical representation of TDHF results promises to make the molecular TDHF approach a very viable tool for the study of reactive molecular scattering.

• Research Organization: California Univ., Davis, CA (USA)
• OSTI ID: 6054270
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ARRAY PROCESSORS
CHARGE EXCHANGE
CHARGED PARTICLES
COLLISIONS
DIFFERENTIAL EQUATIONS
ELEMENTS
ENERGY-LEVEL TRANSITIONS
EQUATIONS
EQUATIONS OF MOTION
FUNCTIONS
HARTREE-FOCK METHOD
HYDROGEN
HYDROGEN IONS
ION COLLISIONS
ION-MOLECULE COLLISIONS
IONS
MOLECULE COLLISIONS
NONMETALS
PARTIAL DIFFERENTIAL EQUATIONS
PROGRAMMING
SCATTERING
SEMICLASSICAL APPROXIMATION
TIME DEPENDENCE
VECTOR PROCESSING
WAVE FUNCTIONS