A MODITIED HARTREE-FOCK-SLATER MODEL FOR A MATERIAL WITH PRESET TEMPERATURE AND DENSITY

A. F. Nikiforov, V. G. Novikov, V. B. Uvarov
Vant. Ser. Metodiki i Programmy Chislennogo Resheniya Zadach Matematicheskoy Fiziki 1979. Вып.4. С. 16-26.

      A quantum mechanics model is described, which may be used to predict different material properties. Since exchange effects may greatly contribute to thermodynamic functions, a variational law was used to progressively derive an expression for the exchange potential at arbitrary material temperature and density.
      To reduce the computation time, a capability is provided to take into account overlapping strips or unfilled electron states in a quasi-classical approximation. It is shown, that such simplification does not lead to a considerable decrease in calculation accuracy.

      A material equation-of-state is derived, based on the HFS model, and the conditions for thermodynamic model consistency are obtained. It is shown, that taking into account the exchange effects in wave functions may substantially influence the calculational results at low temperatures and densities, close to normal ones. Comparing the results obtained with those of TFP model indicates that shell effects play an important role and may greatly exceed quantum and exchange corrections.

      The paper compares the results of a light absorption calculation with experimental data on Ar plasma for a temperature of 20.000K and densiltes from 10¹⁷ to 10²¹ atom/cm³. To estimate photoionization cross-sections, a method is proposed for calculating matrix elements with rapidly oscillating wave functions.