Elucidating energy disposal pathways following excitation of the symmetric OH stretching band in formic acid dimer

We present time dependent energy distributions following the initial excitation of the symmetric OH stretching band in formic acid dimer. Both a simplified single minimum model and full model are employed. We interpret the results of the wavepacket propagation through a definition of divisions of states which allow for a clear description of energy flow between the primitive OH, dimer and bath degrees of freedom (DOF). Evidence for anharmonic coupling between the dimer and primitive OH modes are seen. We further examine the bath and show that 2:1 Fermi resonances represent the predominant energy disposal pathways.