The implementation of two simple ideas concerning the optimization of a many-electron ground state wavefunction is reported. Firstly, the wavefunction is written as a sum of non-orthogonal Slater determinants. Secondly, the optimization is carried out by adding one determinant at a time and determining the best possible orbitals to be used in that determinant. Technical details of gradient-optimization methods are included. Calculations on the electronic ground state of Be, BH and H2O indicate that near full-CI accuracy can be attained using a comparatively small number of determinants. Finally, it is conjectured that a geminal approach might provide an effective solution to the problem of initiating the optimization sequence for each successively added determinant. © 1993.
Linear superposition of optimized non-orthogonal Slater determinants for singlet states
Koch, Henrik;
1993
Abstract
The implementation of two simple ideas concerning the optimization of a many-electron ground state wavefunction is reported. Firstly, the wavefunction is written as a sum of non-orthogonal Slater determinants. Secondly, the optimization is carried out by adding one determinant at a time and determining the best possible orbitals to be used in that determinant. Technical details of gradient-optimization methods are included. Calculations on the electronic ground state of Be, BH and H2O indicate that near full-CI accuracy can be attained using a comparatively small number of determinants. Finally, it is conjectured that a geminal approach might provide an effective solution to the problem of initiating the optimization sequence for each successively added determinant. © 1993.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
