Want to minimize the energy w.r.t. the wavefunctions
:

- Expand in a basis set:
- For a non-orthogonal basis set, solve the generalized eigenvalue
equation:

- Need to distinguish contravariant and covariant
quantities
^{} - Correct gradient is therefore:

1mm

M. P. Teter, M. C. Payne and D. C. Allan,

D. R. Bowler and M. J. Gillan,

Peter D. Haynes 2001-11-09