Linear response calculation with nonlocal van der Waals density functionals

The linear-response approach with the nonlocal van der Waals density functionals is presented, considering three kinds of perturbations: Atomic displacements, uniform electric fields, and strain. The formulas to compute the response with respect to strain are derived for the van der Waals density functionals as well as for the generalized gradient approximation. The linear-response method is implemented within the ultrasoft pseudopotential scheme. The method is applied to weak-coupled layered materials, graphite and MoS2. The results support the validity of the derived formulas and demonstrate the utilities of the linear-response method for weak-coupled van der Waals systems.

Automated summary

This paper presents the linear-response approach using the nonlocal van der Waals density functionals, considering three types of perturbations: atomic displacements, uniform electric fields, and strain. Formulas for calculating the response to strain are derived for both the van der Waals density functionals and the generalized gradient approximation. The linear-response method is implemented within the ultrasoft pseudopotential scheme. The method is applied to weakly coupled layered materials, such as graphite and MoS2, and the results confirm the validity of the derived formulas and demonstrate the utility of the linear-response method for weakly coupled van der Waals systems.