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RELAX drives and controls a non-linear optimization procedure to
locate the minimum (or a stationary point) of a function
mathend000# is always the electronic energy, and the coordinates
mathend000# will be referred to as general coordinates. They include
The optimization employs an iterative procedure based on gradients
mathend000# of the current and, if available, previous iterations.
Various procedures can be applied: steepest descent, Pulay's
DIIS, quasi-Newton, conjugate
gradients, as well as combinations of them.
RELAX carries out:
- cartesian atomic coordinates
- internal atomic coordinates
- exponents, contraction coefficients and scaling factors of basis
- a global scaling factor (a common scaling factor for all basis
The mode of operation is chosen by the keywords $optimize and
$interconversion and the corresponding options, which will
be described in the following sections.
- update of general coordinates
- update of approximate hessians if needed
- conversion of coordinates (internal