Browsing by Author "B. Padhy"

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Double electron excitation in heliumlike ions
(1983) B. Padhy; R. Srivastava; D.K. Rai
A Coulomb-Born-Oppenheimer approach to the calculation of cross sections for electronimpact excitation of the doubly excited 2p2 P3 state in heliumlike ions is presented. It is shown that closed-form expressions can be obtained for both differential and total cross sections. The analysis is applied to calculate the total cross section for the process e-+Li+(1s2 S1)e-+Li+(2p2 P3). © 1983 The American Physical Society.
Glauber amplitude for scattering of electrons by hydrogen atoms: 1s'2s,2p excitations
(1988) B. Padhy; D.K. Rai
The method proposed by Yates [Chem. Phys. Lett. 25, 480 (1974)] has been extended to the case of 1s'2s,2p excitation of a hydrogen atom by electron impact. An alternative analytical procedure used by Berestetskii, Lifshitz, and Pitaevskii [Quantum Electrodynamics (Pergamon, Oxford, 1982), p. 539] has, however, been adopted for the evaluation of the third term of the Glauber series. In the process Yates's expression for the third Glauber term for electron"hydrogen-atom elastic scattering has been reproduced. The differential scattering cross section for the excitation process has been calculated as suggested by Yates. This cross section is found to be in reasonable agreement in the low-angle region with the exact Glauber results reported by Tai et al. [Phys. Rev. A 1, 1819 (1970)] and by Gien [Phys. Rev. A 20, 1457 (1979)]. © 1988 The American Physical Society.
Two-electron excitation in helium-like ions by electron impact
(Springer India, 1990) B. Padhy; D.K. Rai
Calculation of cross-sections for the two-electron excitation in helium-like ions by electron impact employing Coulomb-Born-Oppenheimer (CBO) approximation is presented. Analytical expressions for the differential and total scattering cross-sections without using partial wave expansion of the wavefunction reported earlier have been used. The total and differential scattering cross-sections for each of the excitations 1 s 2 1 S* → 2 s 2 1 S e, 2 s2 p 1.3 P 0, 2 p 2 1 S e,3 P e,1 D e in Be2+ and B3+ are computed. Results for Li+ reported earlier are also included for comparison. © 1990 the Indian Academy of Sciences.
Two-parameter wavefunction for the ground state of the helium isoelectronic sequence
(1995) D.N. Tripathy; B. Padhy; D.K. Rai
A simple two-parameter wavefunction for the ground state of two-electron atoms has been obtained by introducing variational parameters in the Hamiltonian rather than in the trial wavefuncLon The energy eigenvalues have been calculated for atoms with nuclear charge Z in the range i < Z < 12. The binding energies so obtained are observed to be better than the corresponding one-parameter {only screening} values, and are in reasonable agreement with very accurate multiparameter results reported by earlier workers. The method proposed is only easily extendable to those configurations in which both the electrons occup> the same orbital. © 1995 IOP Publishing Ltd.