First principles calculation of finite temperature magnetism in Fe and Fe3C

Density functional calculations have proven to be a useful tool in the study of ground state properties of many materials. The investigation of finite temperature magnetism, on the other hand, has to rely usually on the usage of empirical models that allow the large number of evaluations of the syst...

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Bibliographic Details
Published in:Journal of applied physics 2011-04, Vol.109 (7)
Main Authors: Eisenbach, M., Nicholson, D. M., Rusanu, A., Brown, G.
Format: Article
Language:English
Subjects:
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
COMPUTERS
CURIE POINT
ELECTRONIC STRUCTURE
FREE ENERGY
FUNCTIONALS
GROUND STATES
HAMILTONIANS
MAGNETISM
MAGNETIZATION
MULTIPLE SCATTERING
NEW YORK
PHASE SPACE
SAMPLING
SPECIFIC HEAT
STORAGE
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Summary:Density functional calculations have proven to be a useful tool in the study of ground state properties of many materials. The investigation of finite temperature magnetism, on the other hand, has to rely usually on the usage of empirical models that allow the large number of evaluations of the systems Hamiltonian that are required to obtain the phase space sampling needed to obtain the free energy, specific heat, magnetization, susceptibility, and other quantities as function of temperature. We have demonstrated a solution to this problem that harnesses the computational power of today’s large massively parallel computers by combining a classical Wang–Landau Monte-Carlo calculation [F. Wang and D. P. Landau, Phys. Rev. Lett. 86, 2050 (2001)] with our first principles multiple scattering electronic structure code [Y. Wang et al., Phys. Rev. Lett. 75, 2867 (1995)] that allows the energy calculation of constrained magnetic states [M. Eisenbach et al., Proceedings of the Conference on High Performance Computing, Networking, Storage and Analysis (ACM, New York, 2009)]. We present our calculations of finite temperature properties of Fe and Fe3C using this approach and we find the Curie temperatures to be 980 and 425K, respectively.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.3562218