At 09:02 AM 6/19/99 +0000, you wrote:
>Hi,
>
>Can some one advise on a software to simulate the effect(s) of heat
>(temperature
>application) and that (those) of pressure on a given crystal structure.
>
You do not mention which aspects of the structure you wish to simulate;
however, the short answer is that such software does not exist. The closest
approach would be the ab initio techniques such as LDA or other
density-functional codes. These methods can handle high pressure, but are
generally good only at 0 K. Approximations are needed to calculate the
effects of higher T. In addition, these calculations require a supercomputer.
If the thermal expansitivity and the compressibility are known for the
material in question, one can perform calculations of bond distances, etc.
by assuming that the fractional coordinates remain constant. This
approximation sounds really awful, but is quite good for many
3-dimensionally-linked materials. For molecular materials at modest P
and/or T, you can assume that the molecular geometry is unchanged. The
approximation is better than you might expect.
Sincerely,
Larry
--
Larry W. Finger [EMAIL PROTECTED]
Geophysical Laboratory Phone: +1 (202) 686-2410 X 2464
5251 Broad Branch Road N.W. FAX: +1 (202) 686-2419
Washington, DC 20015-1305, USA
http://www.gl.ciw.edu/~finger/
