Hydrogen Bond in Molecules with Large-Amplitude Motions: A Rotational Study of Trimethylene Sulfide small middle dot small middle dot small middle dotHCl The authors would like to thank the Dirección General de Enseñanza Superior (DGES Grant PB96-0366) and the Junta de Castilla y León (JCL Grants VA51/96 and VA04/98) for support of this work. M.E.S. gratefully acknowledges an FPI grant from the Ministerio de Educación y Cultura