Energetics of the incommensurate phase of krypton on graphite: A computer simulation study

The energetics of the weakly incommensurate phase of a quasi-two-dimensional system of 20 736 krypton atoms on a graphite surface are investigated. We have chosen a krypton-graphite potential which gives the commensurate phase as the lowest-energy state. The energy increase of the incommensurate phase can be described in terms of a hexagonal domain-wall network confirming the phenomenologic description of Bak et al. The wall energy per unit length {ξ} and the energy associated with each wall intersection {Λ} are calculated. Since {Λ} ({Λ}/kB{}-30 K) is significantly negative our results provide strong evidence that the commensurate-incommensurate transition might be first order.