title: Roton-rotation coupling of acetylene in 4He.
abstract: Rotational absorption spectra of acetylene in superfluid 4He calculated using a path-integral correlation function approach are seen to result in an anomalously large distortion constant in addition to a reduced rotational constant, with values in excellent agreement with recent experiments. Semianalytic treatment of the dynamics with a combined correlated basis function-diffusion Monte Carlo method reveals that this anomalous behavior is due to strong coupling of the higher rotational states of the molecule with the roton and maxon excitations of 4He, and the associated divergence of the 4He density of states in this region.
authors.affiliation: Department of Chemistry, University of California, Berkeley, California 94720, USA.
authors.forename: R E
authors.initials: RE
authors.lastname: Zillich
authors.forename: Y
authors.initials: Y
authors.lastname: Kwon
authors.forename: K B
authors.initials: KB
authors.lastname: Whaley