Classical dynamics of dissociative adsorption for a nonactivated system: The role of zero point energy

BUSNENGO, H.F.; CRESPOS, C.; DONG, W.; RAYEZ, J.C.; SALIN, A.

JOURNAL OF CHEMICAL PHYSICS

Año: 2002 vol. 116 p. 9005 - 9013

0021-9606

We present dissociative adsorption probabilities of H2 on Pd 111 computed with the classical trajectory method. We perform both classical C and quasiclassical QC calculations, the latterincluding, by contrast with the former, the initial zero point energy ZPE of H2 . We analyze in detail the role played by the ZPE and demonstrate the strong and weak points of both C and QCcalculations. We show that ZPE is crucial in accelerating the molecules toward the surface through vibrational softening. However, at low energies, dynamic trapping is quenched in QC calculations by processes of vibration to rotation energy transfer that would be associated with closed channels in a quantum approach. In this study we use a new representation of the H2 /Pd(111) potential energy surface obtained by interpolation of ab initio data with a significantly better accuracy in theentrance channel region which plays a decisive role in the dissociation dynamics.