scholarly journals Structure of Sn1−xGex random alloys as obtained from the coherent potential approximation

2011 ◽  
Vol 110 (3) ◽  
pp. 036105 ◽  
Author(s):  
J. J. Pulikkotil ◽  
A. Chroneos ◽  
U. Schwingenschlögl
Keyword(s):  
Coherent Potential Approximation ◽  
Potential Approximation ◽  
Random Alloys

AN AUGMENTED SPACE-BASED CLUSTER COHERENT POTENTIAL APPROXIMATION: APPLICATION TO CuAu AND NiAl ALLOYS

2011 ◽  
Vol 25 (05) ◽  
pp. 735-745
Author(s):  
MOSHIOUR RAHAMAN ◽  
ABHIJIT MOOKERJEE
Keyword(s):  
Magnetic Properties ◽  
Tight Binding ◽  
Local Environment ◽  
Coherent Potential Approximation ◽  
Orbital Method ◽  
Potential Approximation ◽  
Augmented Space ◽  
Space Formalism ◽  
Random Alloys ◽  
Linear Muffin Tin Orbital

We use cluster generalization of the coherent potential approximation in the tight-binding linear muffin-tin orbital method to account for the effect of the local environment on electronic and magnetic properties of substitutional random alloys. This theory combines the augmented space formalism and conventional tight-binding linear muffin-tin orbital methods. In particular, we shall apply the technique to the bcc-based NiAl and fcc-based CuAu alloys and also compare with other approaches.

Ordering Energy of B2 Alloys Calculated in the Frozen Potential and Harris Approximations

1990 ◽  
Vol 186 ◽  
Author(s):  
W. A. Shelton ◽  
D. M. Nicholson ◽  
G. M. Stocks ◽  
F. J. Pinski ◽  
D. D. Johnson ◽  
...  
Keyword(s):  
Long Range ◽  
Natural Extension ◽  
Coherent Potential Approximation ◽  
Range Order ◽  
Single Site ◽  
Long Range Order ◽  
Potential Approximation ◽  
Charge Densities ◽  
Ordered Alloys ◽  
Random Alloys

AbstractIt has been established that the coherent potential approximation can successfully describe the energy of random alloys [1]. It has also served as the basis of generalized perturbation method [2] and concentration wave [3] xscalculations of the energy of short range ordered alloys. The multisublattice coherent potential, (MCPA) is the natural extension of the CPA with which to address long range order (LRO). Using the recently developed multisublattice coherent potential approximation Korringa Kohn Rostoker [4], (MCPA-KKR) code the elgenvalue sum can be calculated as a function of LRO. This allows the evaluation of the ordering energy by either of two approximations. The frozen potential approximation (FPA) [5] assumes that the muffintin single site potentials do not change as the long range order is varied; the Harris Approximation, (HA) [6], as applied in this work, assumes that the single site charge densities do not change as the long range order is changed. These two methods of calculating the ordering energy will be compared with each other and to experiment for several systems including CuZn, NiAl, and NiAl with zinc additions.

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