Kar, S, Ho YK.
2008.
Dipole polarizabilities of plasma-embedded Ps− and H− ions. Physics Letters A. 372:4253-4256., Number 23
AbstractWe have investigated the effect of weakly coupled hot plasmas on the dipole polarizabilities of positronium negative ion and hydrogen negative ion. The plasma effect is taken care of by employing a screened Coulomb (Yukawa) potential of Debye type, and highly correlated exponential wave functions are used. Dipole polarizabilities for various screening parameters are reported.
Kar, S, Ho YK.
2008.
Dispersion coefficients for interactions between positronium and light atoms with pure Coulomb and screened Coulomb potentials. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms. 266:526-529., Number 3
AbstractThe Van der Waals two-body dispersion coefficients for interactions between the positronium (Ps) atom and light atoms have been investigated using highly correlated exponential basis functions in the framework of both pure Coulomb and screened Coulomb potentials. The C6, \{C8\} and \{C10\} coefficients for Ps–Ps and Ps–H interactions, and the \{C6\} coefficients for Ps–He interactions for both the screened and unscreened cases, are reported.
Kar, S, Ho YK.
2008.
Resonance states of three self-gravitating bosons and fermions below the N = 3 threshold of the two-body subsystem. Journal of Physics B: Atomic, Molecular and Optical Physics. 41:065302., Number 6
AbstractThe resonance states of systems consisting of three identical bosons and three fermions interacting with an attractive 1/ r potential are investigated using highly correlated exponential basis functions. The method of complex-coordinate rotation is used to extract energies and widths for the resonances lying below the N = 3 excited state threshold of the respective two-body subsystem. We have obtained a total of 24 S-wave resonances for the three-boson system and a total of 19 S-wave resonances in total spin-3/2 (the 4 S state) and a total of 15 S-wave resonances in total spin-1/2 (the 2 S state) below the N = 3 threshold. For the resonances associated with the N = 3 threshold, we have obtained two, three and four series of Rydberg states for the three-boson system, three-fermion system for 2 S states and three-fermion system for 4 S states, respectively. The resonance energies and widths of these states for the three-body self-gravitating bosons and fermions are reported.
Kar, S, Ho YK.
2008.
Unnatural parity states of helium with screened Coulomb potentials. International Journal of Quantum Chemistry. 108:1491–1504., Number 9: Wiley Subscription Services, Inc., A Wiley Company
AbstractEffect of screened Coulomb (Yukawa) potentials on the doubly excited meta-stable bound states and the resonance states with unnatural parities of the helium atom have been investigated in the framework of stabilization method using CI-type basis functions. A total of 54 resonances (6 each of 1Do and 3Do states, 12 each of 1Fe and 3Fe states, 9 each of 1Go and 3Go states) below the He+(3P) thresholds have been estimated by calculating the density of resonance states using a stabilization method. The resonances belong to the different 3lnl′ (n ≥ 3) series. We have also calculated the doubly excited 1,3Fe and 1,3Go meta-stable bound states of He atom below the He+ (2P) thresholds. The resonance energies and widths along with the meta-stable bound states energies are reported for various screening parameters. In free atom case, some of the F-wave resonance states and most of the cases, F- and G-wave resonance widths are reported for the first time. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
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