Interfacing relativistic and nonrelativistic methods .1. Normalized elimination of the small component in the modified Dirac equation

被引:325
作者
Dyall, KG
机构
[1] Thermosciences Institute, NASA Ames Research Center, Mail Stop 230-3, Moffett Field
关键词
D O I
10.1063/1.473860
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The introduction of relativistic terms into the nonrelativistic all-electron Schrodinger equation is achieved by the method of normalized elimination of the small component (ESC) within the matrix representation of the modified Dirac equation. In contrast to the usual method of ESC, the method presented retains the correct relativistic normalization, and permits the construction of a single matrix relating the large and small component coefficient matrices for an entire set of positive energy one-particle states, thus enabling the whole set to be obtained with a single diagonalization. This matrix is used to define a modified set of one- and two-electron integrals which have the same appearance as the nonrelativistic integrals, and to which they reduce in the limit alpha-->0. The normalized method corresponds to a projection of the Dirac-Fock matrix onto the positive energy states. Inclusion of the normalization reduces the discrepancy between the eigenvalues of the ESC approach and the Dirac eigenvalues for a model problem from order alpha(2) to order alpha(4), providing a closer approximation to the original, uneliminated solutions. The transition between the nonrelativistic and relativistic limits is achieved bq simply scaling the fine structure constant alpha. (C) 1997 American Institute of Physics.
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页码:9618 / 9626
页数:9
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