Bosonized squeezed-state coupled-cluster approach to electron correlations in nonlinear spectroscopy

摘要: The signatures of excited-state correlations in the third-order optical response many-electron systems are calculated using a time-dependent quasiparticle picture which maps excitations onto system interacting bosons, following transformation to boson (oscillator) variables. many-body wavefunction is approximated by Gaussian wavepacket representing squeezed state space. Unlike standard coupled-cluster technique, present approach constitutes generalized coherent representation makes it possible derive simple closed equations motion for its parameters. Hartree–Fock approximation recovered weakly correlated where squeezing negligible.