High Pressure Study on the Absorption Spectra of Lithium Doped in Solid H2

We employ quantum path-integral Monte Carlo method to investigate the pressure-induced absorption spectra of Li in solid H2 at T=5 K and pressure ranging from 0 to 2.4 GPa, based on Lax's semiclassical spectral line theory. The pressure-induced effects on Li atomic absorption spectra associate with an increase in half-width and a centroid spectral shift, which experiences a blue shift below a turning pressure (pt) and a red shift above pt under study. For lower symmetrical trapping site structures, application of pressure also results in a change in absorption line shape from a low symmetrical triplet feature to a doublet plus singlet pattern, in which the doublet to singlet splitting increases remarkably with the increasing of pressure.