Electronic charge density in helium in the first order shielding approximation

Electronic charge density for ground state of helium as function of nuclear charg

Some Remarks on the Use of the Variational Principle for the Second Order Energy

Approximate ground state wave function used in variational principle for second order energ

The variational method 2 - Perturbation theory

Variational method to approximate solutions of perturbation equations, perturbation analyses, and use of perturbation theory to infer variational principl

Theorems satisfied by variational wave functions in scattering theory

Various theorems in the theory of spinless particle scattering by a real central potential are derived directly from the Kohn variational principle

Two notes on perturbation theory. 1 - Interchange theorems and the variation principle. 2 - PV in a different notation

Interchange theorems and variational principle in perturbation theor

Gauge invariance, current conservation, and GIAO's

The well known relationship between gauge invariance and current conservation is exhibited within the usual quantum mechanical formalism. It is then shown that the use of gauge-invariant atomic orbitals (GIAO) does not necessarily lead to the expected current conservation. The reason is found to lie in the constrained nature of the gauge invariance which is provided by the use of GIAO's. It is concluded that this invariance is, of itself, no argument in favor of their use

Improvement of uncoupled Hartree-Fock expectation values for physical properties, II

Improvement of uncoupled Hartree-Fock expectation values for physical propertie