Accurate Treatment of Energetics and Geometry of Carbon and Hydrocarbon Compounds within Tight-Binding Model.

We show that a simple noniterative tight-binding model can provide reliable estimates of energetics and geometries of molecules with C-C and C-H bonds. The mean absolute error in heats of formation, ∼4.6 kcal/mol, is essentially smaller than those found in previous tight-binding schemes. The internal consistency of the calculated heats of formation enables the reliable prediction of bond dissociation energies and isomerization enthalpies. The model gives accurate molecular geometries of hydrocarbons; the mean absolute errors in bond lengths and bond angles are 0.015 Å and 1.4°, respectively. The calculated vibration frequencies agree reasonably well with experimental values. The method has proven to be transferable to complex carbon and hydrocarbon systems. The good performance of the model and its computational efficiency make it promising for simulations of carbon and hydrocarbon systems.