Accurate prediction of the properties of materials using the CAM-B3LYP density functional

Density functionals with asymptotic corrections to the long-range potential provide entry-level methods for calculations on molecules that can sustain charge transfer, but similar applications in materials science are rare. We describe an implementation of the CAM-B3LYP range-separated functional within the Vienna Ab-initio Simulation Package (VASP) framework, together with its analytical functional derivatives. Results obtained for eight representative materials: aluminum, diamond, graphene, silicon, NaCl, MgO, 2D h-BN, and 3D h-BN, indicate that CAM-B3LYP predictions embody mean-absolute deviations (MAD) compared to HSE06 that are reduced by a factor of six for lattice parameters, four for quasiparticle band gaps, three for the lowest optical excitation energies, and six for exciton binding energies. Further, CAM-B3LYP appears competitive compared to ab initio G(0)W(0) and Bethe-Salpeter equation approaches. The CAM-B3LYP implementation in VASP was verified by comparison of optimized geometries and reaction energies for isolated molecules taken from the ACCDB database, evaluated in large periodic unit cells, to analogous results obtained using Gaussian basis sets. Using standard GW pseudopotentials and energy cutoffs for the plane-wave calculations and the aug-cc-pV5Z basis set for the atomic-basis ones, the MAD in energy for 1738 chemical reactions was 0.34 kcal mol(-1), while for 480 unique bond lengths this was 0.0036 angstrom; these values reduced to 0.28 kcal mol(-1) (largest error 0.94 kcal mol(-1)) and 0.0009 angstrom by increasing the plane-wave cutoff energy to 850 eV.

Automated summary

Density functionals with asymptotic corrections, such as the CAM-B3LYP range-separated functional, show promising results in material science calculations. Compared to other methods, CAM-B3LYP exhibits higher accuracy and efficiency in predicting properties of various materials.