Assessment of quantum-chemical methods for electronic properties and geometry of signaling biomolecules

A reasonable balance between accuracy and feasibility of quantum-chemical methods depends on the complexity of the molecular system and the scientific goals. Six series of indole-, naphthalene-, phenol-, benzoic-, phenoxy-, other auxin-derivatives, and a test set of similar organic molecules have been chosen for an assessment of 13 density functional and semi-empirical molecular orbital methods with respect to electronic and structural properties. The accuracy and precision of HOMO/LUMO calculations are determined by comparison with experimental ionization potentials and electron affinities. Further comparison was performed at atomic level by covariance analysis. The methods KMLYP, MSINDO, and PM3 are precise and accurate for the whole set of molecules. The method AM1 offers comparable accuracy with the exception of electron affinities of indole derivatives, where significant deviations from experiment were observed. Geometrical properties were best reproduced with the semi-empirical method MSINDO.