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Properties of basis set

Single parameter $E_{\rm {cut}}$ can be used to control the completeness
Basis functions within a sphere are mutually orthogonal
For basis functions in different spheres, analytic results can be obtained for:
- overlap matrix elements
- kinetic energy matrix elements
- non-local pseudopotential (in Kleinman-Bylander form) matrix elements:

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$\begin{picture}(240,70) \put(10,50){$ {\hat V}_{\rm {NL}} = \displaystyle{\sum_{... ...ll m}^{\rm{ps}}$}} \put(179,38){$r_{\mathrm c}$} \put(212,41){$r$} \end{picture}$

Peter D. Haynes 2001-11-09