Kohn-Rostoker variational principle

2 Variational principles 7.2.1 Kohn-Rostoker variational principle 

In a true scattering problem, an incident wave is specified, and scattered wave components of ifr are varied. In MST or KKR theory, the fixed term x in the full Lippmann-Schwinger equation, f = x + / GqVms required to vanish, x is a solution of the Helmholtz equation. In each local atomic cell r of a space-filling cellular model, any variation of i// in the orbital Hilbert space induces an infinitesimal variation of the KR functional of the form 8 A = fr Govi/s) + he. This 

In a finite basis of primitive functions (/ , the stationary condition is 

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The Kohn-Rostoker variational principle [204] implies variational equations in the extended basis , . Each energy-independent ACO basis function k is defined by one fixed function equations indexed by 4>K in cell r/x for the coefficients in fk are... 

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