Efficient and accurate ab initio prediction of thermodynamic parameters for intermolecular complexes

Recently proposed protocol for accurate (errors within about 1 kcal/mol of experimental data) prediction of the thermodynamic parameters of intermolecular interactions have been tested against other DFT, MP2 and CCSD(T) based methods for complexes including GC and AT DNA base pairs. Newly optimized procedure comprising of two steps proved itself as good compromise between computational demand and chemical accuracy. The first step of proposed protocol involves the counterpoise corrected optimization and calculation of harmonic frequencies at B3LYP/cc-pVTZ level. The second step consists of single point MP2 (cc-pVDZ and cc-pVTZ) calculations and extrapolation to the complete basis set limit.