MOLECULAR-DYNAMICS SIMULATION OF THE INFRARED-SPECTRUM OF ULTRAFAST INTERCONVERTING GEOMETRICAL-ISOMERS

The effect of ultrafast interconversion of geometrical isomers on the infrared spectrum was obtained through MD simulation. Arresting the in terconversion by the introduction of a very high barrier allowed excha nge broadening in the absence of that barrier to be demonstrated convi ncingly. The spectra obtained could ah be fitted very well with Bloch lineshapes, and the lifetimes extracted in this way agreed well with t hose obtained directly from the simulation except in those cases where the interconversion rate was too slow or too fast. A preliminary atte mpt to study not only barrier height effects on ultrafast rates in sol ution but also those of barrier shape has been made.