Hyperpolarizability of two electron atoms under spherically confined Debye plasma

Abstract

Pilot calculations on the hyperpolarizability of He, the first neutral member of the two electron sequence, have been performed under spherical confinement with a view to analyse the effect of pressure on such non linear optical properties. Detailed investigations have also been performed for the first time on the hyperpolarizability due to the effect of screened Coulomb potential obtained from a surrounding Debye plasma environment. Variation perturbation theory within coupled Hartree-Fock scheme has been adopted to estimate the non linear optical properties under such external confinement. For a given plasma coupling strength, the hyperpolarizability value is found to reduce systematically with decrease of radius of confinement, while the same is found to increase continuously with increasing plasma coupling strength determined by gradual enhancement of the screening parameter for a given radius of confinement. Under strong confinement the hyperpolarizability value is found to be negative. The estimated free atom hyperpolarizability is consistent with the existing coupled Hartree-Fock result.