Simulation of the (H2O)8 cluster with the SCC-DFTB electronic structure method

The self-consistent-charge density-functional tight-binding electronic structure method with H-bonding, third order, and dispersion corrections (SCC-DFTB+D [HB+third]) have been applied to the (H2O)8 cluster. Low-lying potential energy minima of (H2O)8 determined using the basin hopping Monte Carlo method have been located and compared with results of ab initio second-order Møllet–Plesset perturbation (MP2) methods. Parallel-tempering Monte Carlo simulations have been used to characterize the finite temperature behavior of the (H2O)8 cluster. Compared to the results of the original SCC-DFTB+D method, the thermodynamic properties as well as the energetics of the low-lying minima using H-bonding and third order corrections more closely reproduces those reported previously using model potentials and MP2 calculations.