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Nonlinear response properties of atomic hydrogen under quantum plasma environment: A time‐dependent variation perturbation study on hyperpolarizability and two‐photon excitations
Author(s) -
Bhattacharyya Sukhamoy,
Mukherjee Prasanta K.,
Fricke Burkhard
Publication year - 2020
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.26422
Subject(s) - hyperpolarizability , excited state , atomic physics , physics , ground state , wave function , perturbation theory (quantum mechanics) , hydrogen atom , oscillator strength , quantum , quantum mechanics , nonlinear system , chemistry , spectral line , nonlinear optical , group (periodic table)
Abstract Pilot calculations on the frequency‐dependent nonlinear response property, viz. the electric dipole hyperpolarizability of atomic hydrogen under quantum plasma environment, have been performed using an external oscillatory electric field. Fourth‐order perturbation theory within a variational scheme is adopted to obtain the hyperpolarizability within and beyond normal dispersion region. Two‐photon absorption from the ground state is explicitly obtained from the pole positions of nonlinear response of the system and studied up to principal quantum number n = 4 . Ground and perturbed wave functions of appropriate symmetries are represented by linear combination of Slater‐type orbitals. Exponential cosine‐screened Coulomb potential is used to simulate the quantum plasma environment. With respect to plasma strength, the nonlinear response properties are considerably enhanced. Results are compared with those under classical plasma environment represented by screened Coulomb potential. Departure from Coulomb potential results in lifting of the accidental degeneracy in the respective two‐photon excited states beyond n = 2 . For free hydrogen atom, the transition energies and the radial density profiles of the respective two‐photon excited states match exactly with those obtained from analytical wave functions.