Constant-volume pair potential for Al-transition-metal compounds

J. Zou, A. E. Carlsson

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

We treat the problem of two transition-metal atoms embedded in Al by means of a simple s-d model Hamiltonian with localized d orbitals. A Green's-function analysis gives the electronic density of states and total energy as functions of the separation between the two transition-metal atoms. The pair potential thus obtained is strong and has Ruderman-Kittel-Kasuga-Yosida-type oscillations as its asymptotic behavior. It is applicable to cases in which transition metals are not nearest neighbors. With this pair potential, we calculate the structural energy differences of Al3M compounds in the L12 and DO22 structures, where M includes all of the group III, IV, V transition metals and the whole 4d row. Comparison with ab initio results reveals good agreement for the transition metals in group V and beyond, but not for the earlier transition metals, in which the p-d covalent bonding and three-body interactions are likely more important. We also calculate the (100) antiphase boundary (APB) energies for Al3V, Al3Nb, and Al3La, and find a strong correlation between the APB energy and the structural energy difference. The low-order moment-expansion method is used to obtain short-ranged potentials in an effort to obtain better convergence for the structural energies. This approach fails, giving magnitudes for the structural energy differences that are much too small.

Original languageEnglish
Pages (from-to)2961-2969
Number of pages9
JournalPhysical Review B
Volume47
Issue number6
DOIs
StatePublished - 1993

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