Empirical Valence Bond Simulations of Biological Systems

The empirical valence bond (EVB) approach is a unique hybrid quantum mechanical molecular mechanical (QM/MM) approach with various clear advantages. It facilitates the understanding of reaction mechanisms in biological systems; the calibration of the approach together with its comparative nature often guarantees more accurate results. Furthermore, the simplicity of the potential energy surface enables highly efficient sampling, which is important when particularly large systems or averages over considerably large configuration ensembles are of interest. The EVB approach also provides simple definition of the reaction coordinate, which includes all the system's degrees of freedom. Finally, the method benefits from the valence bond character of the wavefunction, which includes easily accessible chemical insight. As such the EVB contributes considerably to our understanding of complex biological problems. In this review we will discuss these different capabilities of the method while highlighting the advantages of the method over other standard (MO based) QM/MM approaches.