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ID 18641
file
creator
Itami, Toshio
Masaki, Tadahiko
Aoki, Hirokatsu
Ishii, Yasushi
Kamiyama, Takashi
Senda, Yasuhiro
Shimojo, Fuyuki
abstract
The structure of liquid Sn was studied by neutron scattering experiments in the widest temperature range that was ever performed. Though, on increasing temperature, the existence of the shoulder in the structure factor, S(Q), becomes less clear in the change of the overall shape of the S(Q), the structure related to this shoulder seems to be present even at 1873 K. The first-principle molecular-dynamics ~FPMD! simulation was performed for the first time for liquid Sn by using the cell size of 64 particles. The calculated results well reproduced S(Q) obtained by the neutron experiments. The angle distribution, g(3)(u ,rc), was evaluated for the angle between vectors from centered atom to other two atoms in spheres of cutoff radii rc's. The g(3)(u ,rc) shows that, with the decrease of rc from 0.4 to 0.3 nm, a rather sharp peak around 60 ° disappears and only a broad peak around 100 ° remains; the former peak may be derived from the feature of the closely packed structures and the latter one is close to the tetrahedral angle of 109 °. In addition, the coordination number, n, of liquid Sn counted within the sphere of rc=0.3 nm is found to be 2–3 and does not change with the increase of temperature even up to 1873 K. These facts indicate that at least the fragment of the tetrahedral unit may be essentially kept even at 1873 K for liquid Sn. For comparison, the FPMD simulation was performed for the first time also for liquid Pb. No sign of the existence of the tetrahedral structure was observed for liquid Pb. Unfortunately, the self-diffusion coefficients, D's, obtained from this FPMD for liquid Sn do not agree with those obtained by the microgravity experiments though the structure factors, S(Q)'s, are well reproduced. To remove the limitation of the small cell size of the FPMD, the classical molecular-dynamics simulations with a cell size of 2197 particles were performed by incorporating the present experimental structural information of liquid Sn. Obtained D's are in good agreement with the microgravit
journal title
Physical Review B - Condensed Matter and Materials Physics
volume
Volume 67
issue
Issue 6
date of issued
2003-02-10
publisher
American Physical Society
issn
1098-0121
ncid
publisher doi
language
eng
nii type
Journal Article
HU type
Journal Articles
DCMI type
text
format
application/pdf
text version
publisher
rights
Copyright (c) 2003 American Physical Society.
relation url
department
Graduate School of Integrated Arts and Sciences