title: Relationship between structural order and water-like anomalies in metastable liquid silicon: Ab initio molecular dynamics.
abstract: The relationship between structural order and water-like anomalies in tetrahedral liquids is still open. Here, first-principle molecular dynamics are performed to study it in metastable liquid Si. It is found that in T-P phase diagram, there indeed exists a structural anomaly region, which encloses density anomaly but not diffusivity anomaly. This is consistent with that of SW Si and BKS SiO2but different from that of SPC/E water. Two-body excess entropy anomaly can neither capture the diffusivity, structural, and density anomalies, as it can in a two-scale potential fluid. In structural anomaly region, tetrahedrality order qtetra(measuring the extent to which an atom and its four nearest neighbours adopt tetrahedral arrangement) and translational order ttrans(measuring the tendency of two atoms to adopt preferential separation) are not perfectly correlated, which is different from that in SW Si and renders it impossible to use the isotaxis line to quantify the degree of structural order needed for water-like anomalies to occur. Along the isotherm of critical temperature Tc, ttrans/qtetrais approximately linear with pressure. With decreasing pressure along the isotherm below Tc, ttrans/qtetradeparts downward from the line, while it is the opposite case above Tc.
authors.affiliation: School of Physics and Optoelectronic Engineering, Ludong University, Yantai 264025, P. R. China.
authors.forename: G
authors.initials: G
authors.lastname: Zhao
authors.affiliation: School of Physics and Optoelectronic Engineering, Ludong University, Yantai 264025, P. R. China.
authors.forename: J L
authors.initials: JL
authors.lastname: Yan
authors.affiliation: School of Physics and Optoelectronic Engineering, Ludong University, Yantai 264025, P. R. China.
authors.forename: Y J
authors.initials: YJ
authors.lastname: Yu
authors.affiliation: School of Physics and Optoelectronic Engineering, Ludong University, Yantai 264025, P. R. China.
authors.forename: M C
authors.initials: MC
authors.lastname: Ding
authors.affiliation: School of Physics and Optoelectronic Engineering, Ludong University, Yantai 264025, P. R. China.
authors.forename: X G
authors.initials: XG
authors.lastname: Zhao
authors.affiliation: School of Physics and Optoelectronic Engineering, Ludong University, Yantai 264025, P. R. China.
authors.forename: H Y
authors.initials: HY
authors.lastname: Wang