ghostbasisberekeningen

Ghostbasisberekeningen, or ghost basis calculations, are a computational chemistry technique used to mitigate the basis set superposition error (BSSE) in calculations of intermolecular interactions. BSSE arises when the basis set used for one molecule in a complex is also used to describe the electrons of the other molecule. This can artificially lower the calculated interaction energy, making the interaction appear stronger than it truly is.

The ghost basis correction method involves performing additional calculations. In a standard calculation of an interaction between molecule A and molecule B, the total energy is calculated using the basis set of A and B combined. To correct for BSSE, ghost basis calculations involve an auxiliary calculation where molecule A is calculated using its own basis set, but with the atomic centers of molecule B present but without their basis functions. Similarly, molecule B is calculated using its own basis set, with the atomic centers of molecule A present but without their basis functions.

The counterpoise correction, a common type of ghost basis calculation, uses the energy of these augmented basis set calculations to estimate and subtract the BSSE. The counterpoise corrected interaction energy is then obtained by subtracting the BSSE correction from the raw interaction energy. This method provides a more accurate representation of the binding energy between molecules, particularly for weakly interacting systems where BSSE can be significant. Ghost basis calculations are widely employed in studies of hydrogen bonding, van der Waals complexes, and other non-covalent interactions.