title: Nesting of thermodynamic, structural, and dynamic anomalies in liquid silicon.
abstract: Anomalous behaviour in density, diffusivity, and structural order is investigated for silicon modeled by the Stillinger-Weber potential by performing molecular dynamics simulations. As previously reported in the case of water [J. R. Errington and P. G. Debenedetti, Nature (London) 409, 318 (2001)] and silica [M. S. Shell, P. G. Debenedetti, and A. Z. Panagiotopoulos, Phys. Rev. E 66, 011202 (2002)], a cascading of thermodynamic, dynamic, and structural anomalous regions is also observed in liquid silicon. The region of structural anomaly includes the region of diffusivity anomaly, which in turn encompasses the region of density anomaly (which is unlike water but similar to silica). In the region of structural anomaly, a tight correlation between the translational and tetrahedrality order parameter is found, but the correlation is weaker when a local orientational order parameter (q3) is used as a measure of tetrahedrality. The total excess entropy and the pair correlation entropy are computed across the phase diagram and the correlation between the excess entropy and the regions of anomalies in the phase diagram of liquid silicon is examined. Scaling relations associating the excess entropy with the diffusion coefficient show considerable deviation from the quasi-universal behaviour observed in hard-sphere and Lennard-Jones liquids and some liquid metals. Excess entropy based criteria for diffusivity and structural anomalies fail to capture the observed regions of anomaly.
authors.affiliation: Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur Campus, Bengaluru 560 064, India.
authors.forename: Vishwas V
authors.initials: VV
authors.lastname: Vasisht
authors.affiliation: Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, India.
authors.forename: John
authors.initials: J
authors.lastname: Mathew
authors.affiliation: TIFR Centre for Interdisciplinary Sciences 21, Brundavan Colony, Narsingi, Hyderabad 500075, India.
authors.forename: Shiladitya
authors.initials: S
authors.lastname: Sengupta
authors.affiliation: Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur Campus, Bengaluru 560 064, India.
authors.forename: Srikanth
authors.initials: S
authors.lastname: Sastry