Equivalent positions structure amplitude

The wave function has the same amplitude at equivalent positions in each unit cell. Thus, the full electronic structure problem is reduced to a consideration of just the number of electrons in the unit cell (or half that number if the electronic orbitals are assumed to be doubly occupied) and applying boundary conditions to the cell as dictated by Bloch s theorem (Eq. 4.14). Each unit cell face has a partner face that is found by translating the face over a lattice vector R. The solutions to the Schrodinger equation on both faces are equal up to the phase factor exp(zfe R), determining the solutions inside the cell completely. 

Compilation of structural parameters for the surfaces of ordered metallic alloys Afl. Atom type A is the first element listed in the alloy column of the table. is the change in the first inteplanar spacing expressed as a percentage of the (mean) bulk interlayer spacing of the disordered alloy. Mi3 and Ms are the equivalent quantities for deeper layers, bi and bi are the buckling amplitudes in the first and second layers respectively a positive value implies that atom A moves out of its plane towards the surface. 

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