Sp. Rudin et al., Comparison of structural transformations and superconductivity in compressed sulfur and selenium - art. no. 224107, PHYS REV B, 6322(22), 2001, pp. 4107
Density-functional calculations are presented for high-pressure structural
phases of S and Se. The structural phase diagrams, phonon spectra, electron
-phonon coupling, and superconducting properties of the isovalent elements
are compared. We find that with increasing pressure, Se adopts a sequence o
f ever more closely packed structures (beta -Po, bcc, fcc), while S favors
more open structures (beta -Po, simple cubic, bcc). These differences are s
hown to be attributable to differences in the S and Se core states. All the
compressed phases of S and Se considered are calculated to have weak to mo
derate electron-phonon coupling strengths consistent with superconducting t
ransition temperatures in the range of 1 to 20 K. Our results compare well
with experimental data on the beta -Po --> bcc transition pressure in Se an
d on the superconducting transition temperature in beta -Po S. Further expe
riments are suggested to search for the other structural phases predicted a
t higher pressures and to test theoretical results on the electron-phonon i
nteraction and superconducting properties.