COMPARISON OF THE PROJECTOR AUGMENTED-WAVE, PSEUDOPOTENTIAL, AND LINEARIZED AUGMENTED-PLANE-WAVE FORMALISMS FOR DENSITY-FUNCTIONAL CALCULATIONS OF SOLIDS

The projector augmented-wave (PAW) method was developed by Blochl as a method to accurately and efficiently calculate the electronic structu re of materials within the framework of density-functional theory. It contains the numerical advantages of pseudopotential calculations whil e retaining the physics of all-electron calculations, including the co rrect nodal behavior of the valence-electron wave functions and the ab ility to include upper core states in addition to valence states in th e self-consistent iterations. It uses many of the same ideas developed by Vanderbilt in his ''soft pseudopotential'' formalism and in earlie r work by Blochl in his ''generalized separable potentials,'' and has been successfully demonstrated for several interesting materials. We h ave developed a version of the PAW formalism for general use in struct ural and dynamical studies of materials. In the present paper, we inve stigate the accuracy of this implementation in comparison with corresp onding results obtained using pseudopotential and linearized augmented -plane-wave (LAPW) codes. We present results of calculations for the c ohesive energy, equilibrium lattice constant, and bulk modulus for sev eral representative covalent, ionic, and metallic materials including diamond, silicon, SiC, CaF2, fee Ca, and bcc V. With the exception of CaF2, for which core-electron polarization effects are important, the structural properties of these materials are represented equally well by the PAW, LAPW, and pseudopotential formalisms.