Generalized Energy-Based Fragmentation Approach for Structures and Properties of Periodic Condensed Phase Systems

We have presented in this chapter the general formalism of the generalized energy-based fragmentation approach under periodic boundary conditions (PBC-GEBF) and its applications in various types of condensed-phase systems. The PBC-GEBF method is a linear-scaling quantum mechanics (QM) method, in which the ground-state energy per unit of a periodic system is approximately estimated from the ground-state energies of a series of finite subsystems. With PBC-GEBF, post-Hartree–Fock (post-HF) calculations using large basis sets for periodic systems are now easily available. Combined with conventional quantum chemistry programs for molecules, the PBC-GEBF approach is applied to study the lattice energies, crystal structures, vibrational spectra, and NMR parameters for various molecular crystals, ionic crystals or ionic liquid crystals, and liquid systems. Our computational results show that the PBC-GEBF approach can accurately and efficiently provide satisfactory descriptions on the experiment results.