Why can't I find an EAM potential for element X or alloy X-Y?
(21 Dec 2009)
EAM potentials are best suited to free elecron metals, thus copper, silver and
gold are probably the easiest metals to model with EAM; the closer the
resemblence to a free electron metal, the better the fit to the mechanical
properties. It is progressively difficult to create EAM models for systems
that deviate from free electron metals.
XMD supports two non-EAM models for modeling Si (the Stillinger-Weber and
Tersoff potentials) and Si-C (the Tersoff potential).
- 2. What are some references about creating EAM potentials?
(4 April 1997)
- Unfortunately, I know of no complete references for creating
EAM potentials. And it is a long messy business. The best I can do
is recommend papers which describe the creation of specific
potentials. The relevant authors are M. I. Baskes, R. A. Johnson,
A. F. Voter, D. Farkas.
A reference describing our own potentials:
Dislocation Generation and Crack Propagation in Metals Examined
in Molecular Dynamics Simulations; Mat. Res. Soc. Proc.
278:173-178 (1992); Computational Methods in Materials
Science, J. A. Rifkin, C. S. Becquart, D. Kim and P. C.
Also, some references recommended by Furio Ercolessi of http://www.sissa.it/furio. Other
recommendations are welcome.
- ... our early work on Au is summarized with several of the
messy details in F. Ercolessi, M. Parrinello and E. Tosatti,
Philos. Mag. A 58 (1988), 213. As far as I know this is still
the only Au potential which does the Au(100) and Au(111) surface
- ... constructing potentials using ab initio data, which was
published in F. Ercolessi and J. B. Adams, Europhys. Lett. 26
- and there is also a web page at http://www.sissa.it/furio/forcematching.html.
- One of the best reference to put is perhaps A. Carlsson,
Solid State Phys. 43, 1 (1990).
- 3. When varying the lattice parameter, shouldn't the time
averaged potential energy be at a minimum when the time averaged
stress is zero? (Jan 8, 1998)
- No. The Free Energy is a minimum when stress is zero,
not the time-averaged potential energy - except at 0 Kelvin,
when the two quantities are equal.
In particular, the time-averaged potential energy is a minimum
when the stress is zero only when
< s E > = 0
where s is the stress and E is instantaneous
potential energy, and < > represents either the time or