• G Devaiah

      Articles written in Pramana – Journal of Physics

    • The minimax technique in relativistic Hartree-Fock calculations

      S N Datta G Devaiah

      More Details Abstract Fulltext PDF

      Using the set of trial spinors$$\left\{ {N_i \left( {_{\hat \Omega _i u_i }^{u_i } } \right), i = 1, \ldots , N} \right\}$$ and the Dirac-Coulomb Hamiltonian (HDC) we discuss the role of the minimax theorem in relativistic Hartree-Fock calculations. In principle, the minimax theorem guarantees the occurrence of an upper bound. We also consider a scaling of the functionsui and discuss the condition to derive the relativistic hypervirial theorem; the variational procedure represented by the condition serves as an example of the minimax technique. Single zeta calculations onH2+,H2 and He are analysed. The effect of enlarging the basis is investigated for the He atom. The “upper bound” obtained by usingcoherent basis spinors differs from the result of the (random) linear variation using the kinetically balanced basis set by an amount which is at most of orderc−4. Use of thecoherent basis set is advocated.

    • The minimax technique in relativistic Hartree-Fock calculations

      S N Datta G Devaiah

      More Details Fulltext PDF
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