On the Treatment of Link Atoms in Hybrid Methods

Several coupling models and link atom options are investigated for combined quantum-chemical and classical approaches. Ab initio, density functional, and semiempirical methods are used for the quantum-chemical region, whereas the classical region is described by the AMBER force field. Numerical results are reported for the proton affinities of alcohols and ethers. Recommendations for link atoms are given based on these results and theoretical analysis.