title: Wall-induced phase transition controlled by layering freezing.
abstract: Molecular dynamics simulations of the Lennard-Jones model are used to study phase transitions at a smooth surface. Our motivation is the observation that the existence of an attractive wall facilitates crystallization. To investigate how this wall influences phase transitions, the strength of wall-particle interaction is varied in our studies. We find that the phase behavior depends on the strength parameter α, i.e., the ratio between wall-particle and the particle-particle attraction strength. Three critical values of the ratio, namely, αp, αw, and αc, are used to define the qualitative nature of the phase behaviors at a smooth surface. Some interesting phenomena due to the increase of α are observed. First, a set of close-packed planes, i.e., {111} planes in fcc structures or {0001} planes in hcp structures, are "rotated" from intersecting to parallel to the wall when α = αp; second, the layering phase transition close to the wall antecedes that of the bulk when α = αw. Finally, the first-order phase transition in the first two layers is supplanted by a continuous phase transition when α = αc, which to some extent can be treated as a quasi-two-dimensional process. We find that bulk freezing always discontinuously occurs through a first-order phase transition, and seems to be isolated from the freezing process occurring close to the attractive surfaces. Moreover, during the heating process, we observe minimal dependence at a strongly attractive surface.
authors.affiliation: School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, China and Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China.
authors.forename: Huijun
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China.
authors.forename: Shuming
authors.initials: S
authors.lastname: Peng
authors.affiliation: Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China.
authors.forename: Xinggui
authors.initials: X
authors.lastname: Long
authors.affiliation: Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China.
authors.forename: Xiaosong
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Liang
authors.affiliation: School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, China.
authors.forename: Chubin
authors.initials: C
authors.lastname: Wan
authors.affiliation: Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China and School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Zheng
authors.affiliation: School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Ju