Frequency dependent hyperpolarizability and two photon excitations in hydrogen atom confined under classical plasma environment

Nonlinear response properties of atomic hydrogen under quantum plasma environment: A time‐dependent variation perturbation study on hyperpolarizability and two‐photon excitations

“…It is well known that pole positions of frequency-dependent linear polarizability α(ω) furnish accurate representations of single-photon excited states. [31] Manakov et al [32] first pointed out that, for free systems, the pole positions of frequencydependent nonlinear polarizability should furnish two-photon excited states, which was corroborated by the calculations reported in Bhattacharyya et al [1] Experimental studies on polarizability and hyperpolarizability has a long history due to their applications related to linear and nonlinear response properties of atomic systems. [30,[33][34][35][36][37][38] In nonlinear optics, applications of experimentally and theoretically estimated γ(ω) along with the static value for free atoms include dc and ac Kerr effects, optical rectification, electric field-induced second and third harmonic generation, intensity-dependent refractive index, degenerate four-wave mixing, coherent anti-Stokes Raman scattering, etc., and the literature is quite rich.…”

“…Results for H atom under screened Coulomb potential. [1] c Instability region for the two-photon excited state.…”

“…. Following Bhattacharyya et al, [1] we adopt the usual procedure involving expansion of the radial part of the orbital on a finite Slater basis as follows:…”

“…A judicious choice of the exponents is sufficient for achieving converged groundstate energy and eigenvectors for a sufficiently wide range of screening constants. [1] To obtain the frequency-dependent hyperpolarizability γ(ω), we apply a time-dependent harmonic perturbation:…”

“…Theoretical and experimental aspects of NLO response in organic molecules have been analyzed by Bredas et al, [75] and applications exist in noninvasive imaging, three-dimensional optical data storage and optical power limiting, [76] dynamic image processing, holographic imaging, fluorescence optical storage, optical memory, polarization transformers, [77] etc. Two-photon transitions occur as a natural consequence in a frequency-dependent hyperpolarizability calculation, lifting the accidental degeneracy of the excited states with principal quantum number n ≥ 2, and in Bhattacharyya et al, [1] it was discussed with regard to an SCP environment. Only a few recent calculations on two-photon transition amplitudes and transparency amplitudes under classical plasma are available for H-like ions using nonvariational pseudo state and other approaches.…”