TY - JOUR

T1 - Obtaining ising-like expansions for binary alloys from first principles

AU - Zunger, Alex

AU - Wang, L. G.

AU - Hart, Gus L.W.

AU - Sanati, Mahdi

PY - 2002/11

Y1 - 2002/11

N2 - Many measurable properties of crystalline binary A1-x Bx alloys, such as phase diagrams and excess thermodynamic functions, could be predicted via lattice statistical mechanics methods if one knew the 'configurational energy'. The latter describes the energy at T = 0 for each of the 2N possible occupation patterns of the N lattice sites by an A or a B atom. Traditional approaches described the configurational energy either via empirically fitted, truncated Ising Hamiltonians, or through highly approximated coherent-potential constructs. We illustrate here the alternative approach of 'mixed-basis cluster expansion' which extracts from a set of ab initio local density approximation calculations of the total energies of a few ordered A-B compounds a complete configurational energy function. This method includes both pair and multibody terms, whose number and range of interaction are decided by the variational procedure itself, as well as long-range strain terms. In this paper, we describe the computational details of this method, emphasizing methods of construction, interpolations, fits and convergence. This procedure is illustrated for Ni-Pt, Cu-Au and ScS-□S (where □ denotes cation vacancy). The parameters of the final expansions are provided on our webpage (http://www.sst.nrel.gov).

AB - Many measurable properties of crystalline binary A1-x Bx alloys, such as phase diagrams and excess thermodynamic functions, could be predicted via lattice statistical mechanics methods if one knew the 'configurational energy'. The latter describes the energy at T = 0 for each of the 2N possible occupation patterns of the N lattice sites by an A or a B atom. Traditional approaches described the configurational energy either via empirically fitted, truncated Ising Hamiltonians, or through highly approximated coherent-potential constructs. We illustrate here the alternative approach of 'mixed-basis cluster expansion' which extracts from a set of ab initio local density approximation calculations of the total energies of a few ordered A-B compounds a complete configurational energy function. This method includes both pair and multibody terms, whose number and range of interaction are decided by the variational procedure itself, as well as long-range strain terms. In this paper, we describe the computational details of this method, emphasizing methods of construction, interpolations, fits and convergence. This procedure is illustrated for Ni-Pt, Cu-Au and ScS-□S (where □ denotes cation vacancy). The parameters of the final expansions are provided on our webpage (http://www.sst.nrel.gov).

UR - http://www.scopus.com/inward/record.url?scp=0036853423&partnerID=8YFLogxK

U2 - 10.1088/0965-0393/10/6/306

DO - 10.1088/0965-0393/10/6/306

M3 - Article

AN - SCOPUS:0036853423

VL - 10

SP - 685

EP - 706

JO - Modelling and Simulation in Materials Science and Engineering

JF - Modelling and Simulation in Materials Science and Engineering

SN - 0965-0393

IS - 6

ER -