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Section SCF::LCAO
Type integer

(Only applies if LCAOAlternative = no.) Before starting the SCF cycle, an initial LCAO calculation can be performed in order to obtain reasonable initial guesses for spin-orbitals and densities. For this purpose, the code calculates a number of atomic orbitals. The number available for a species described by a pseudopotential is all the orbitals up the maximum angular momentum in the pseudopotential, minus any orbitals that are found to be unbound. For non-pseudopotential species, the number is equal to twice the valence charge. The default dimension for the LCAO basis set will be the sum of all these numbers, or twice the number of required orbitals for the full calculation, whichever is less.

This dimension however can be changed by making use of this variable. Note that LCAODimension cannot be smaller than the number of orbitals needed in the full calculation – if LCAODimension is smaller, it will be silently increased to meet this requirement. In the same way, if LCAODimension is larger than the available number of atomic orbitals, it will be reduced. If you want to use the largest possible number, set LCAODimension to a negative number.

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