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Monomolecular and supermolecular basis set approach

The ρA and ρB densities can be expanded using the supermolecular or monomolecular basis set. In a supermolecular basis set expansion the basis functions {χ} of both subsystems are employed to expand the subsystem electron densities. In a monomolecular basis set expansion, instead, only basis functions {χ$\scriptstyle \ell$} centered on the atoms in the $ \ell$ -th subsystem are used to expand the corresponding density.

Both monomolecular and supermolecular basis set expansion of the electron densities are implemented in FDE: with the flag -m a monomolecular expansion is performed, while for a supermolecular one -s is used. In the absence of both flags a monomolecular expansion is performed by default.

For an accurate calculation of binding-energies of weakly interacting molecular systems a supermolecular basis set is required (to avoid the basis-set superposition error). Otherwise a very large monomolecular basis set is necessary.

NOTE: The FDE script supports only basis-set in the TURBOMOLE library.

Equivalent command: --mono or --super

fde.input option: method=mono or method=super


next up previous contents index
Next: Convergence of the freeze-and-thaw Up: Options Previous: Parallel calculations   Contents   Index
TURBOMOLE M