caa a22 4500 469041463 CHVBK 20180323132812.0 cr unu---uuuuu 170328e19920101xx s 000 0 eng 10.1007/BF02847904 doi (NATIONALLICENCE)springer-10.1007/BF02847904 Datta S. Department of Chemistry, Indian Institute of Technology, 400 076, Bombay, India aut Bound state solutions of the two-electron Dirac-Coulomb equation [Elektronische Daten] [S Datta] We present a variational method for solving the two-electron Dirac-Coulomb equation. When the expectation value of the Dirac-Coulomb Hamiltonian is made stationary for all possible variations of the different components of a well-behaved trial function one obtains solutions representative of the physical bound state wave functions. The ground state wave function is derived from the application of a minimax principle. Since the trial function remains well-behaved, the method remains safe from the twin demons of variational collapse and continuum dissolution. The ground state wave function thus derived can be interpreted as a linear combination of different configurations. In particular, the admixing of intermediate states having one (two) electron(s) deexcited to a negative-energy orbital (orbitals) contributes a second-order level shiftE 0− (2) which can be identified with the second-order shift due to the Pauli blocking of the production of one (or two) virtual electron-positron pair(s). Thus the minimax solution corresponds to the renormalized ground state in quantum electrodynamics, with deexcitations to negative-energy orbitals taking the place of the avoidance of virtual pairs. If one extends the relativistic configuration interaction (RCI) treatment by additionally including negative-energy and mixed-energyeigenvectors of the Dirac-Hartree-Fock hamiltonian matrix in the two-electron basis, the calculated energy will be shifted from the conventional RCI value by an amount that is much smaller thanE 0− (2) . For two-electron atoms, we have derived expressions for the all-spinor limit (δE) and thes-spinor limit (δE s) of this shift in leading orders. The all-spinor limit (δE) is of orderα 4 Z 4 1/3 whereas thes-spinor limit (δE s) is of orderα 4 Z 3 2/3. leading components are related to the 1-pair component ofE 0− (2) in a simple way, and the relationships offer the possibility of computing energy due to virtual pairs. Numerical results are discussed. the Indian Academy of Sciences, 1992 Dirac-Coulomb nationallicence bound state nationallicence minimax technique nationallicence virtual pairs nationallicence 03·65 nationallicence 11·10 nationallicence 31·15 nationallicence Pramana Springer India 38/1(1992-01-01), 51-75 0304-4289 38:1<51 1992 38 12043 https://doi.org/10.1007/BF02847904 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02847904 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Datta S. Department of Chemistry, Indian Institute of Technology, 400 076, Bombay, India aut NATIONALLICENCE 773 0- Pramana Springer India 38/1(1992-01-01), 51-75 0304-4289 38:1<51 1992 38 12043 Metadata rights reserved Springer special CC-BY-NC licence nationallicence SWISSBIB 465041191 BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer