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https://www.ias.ac.in/article/fulltext/pram/083/06/0907-0914

Coulomb interaction; elastic scattering; interatomic potential; dipole–dipole; long range; scattering length; four-centre; ab-initio.

A modified static-exchange model is developed to study the collision of an atom with another atom. It includes the effect of long-range dipole–dipole van der Waals interaction between two atoms in addition to the exact effect of short-range force due to Coulomb exchange between two system electrons. Both these interactions dominate at colder energies. The system is treated as a four-centre problem in the centre-of-mass frame. The present ab-initio model is useful to study the two-atomic collisions at low energies, as well as cold energies. The new code is applied to study the scattering of positronium (Ps) by hydrogen (H), both in their ground states.

Hasi Ray^{1 2 3}

1. National Institute of Technical Teachers’ Training and Research Kolkata, Salt Lake City, Kolkata 700 106, India
2. New Alipore College, New Alipore, Kolkata 700 053, India
3. Study Centre, S-1/407/6, B. P. Township, Kolkata 700 032, India

Published

December 2014

Manuscript received

27 June 2013

Manuscript revised

5 March 2014

Accepted

13 March 2014

Early published

14 September 2014