Theoretical investigation of thermodynamic balance between cluster isomers and statistical model for predicting isomerization rate

Abstract

-By molecular dynamics simulations and free energy calculations based on MonteCarlo method, the detailed balance between Pt cluster isomers was investigated. For clusters of n≤50, stationary equilibrium is achieved in 100 ns in the canonical ensemble, while longer time is needed for n>50. Then, a statistical mechanical model was built to evaluate unimolecular isomerization rate and simplify the prediction of isomer formation probability. This model is simpler than transition state theory and can be easily applied on ab initio calculations to predict the lifetime of nanostructures.

Theoretical investigation on isomer formation probability and free energy of small C clusters

“…In our previous work, we found that for Pt cluster isomers the prediction of free energy criterion is in good agreement with equilibrium molecular dynamics (MD) simulations. [14] However, in the study of C clusters [5,15,16] we found that for C 36 isomers the free energy criterion can only roughly give the differences in formation probability among cage, bowl, and sheet isomers, but fails to quantitatively predict the formation probability of each isomer. [17] In this case, we even develop a time-going-back method [18] and a statistical model [19] to predict C isomer formation probability.…”