A new completely orthogonalized plane waves formalizm in the pseudopotential theory

A new approach based on the completely orthogonalized plane waves (COPW) formalizm is developed in the pseudopotential theory. Utilizing of the complete and orthonormalized basis for the eigenvalue problem solution is the most principled peculiarity of the COPW method. The COPW method allows to perform the similarity transformation of the Schrödinger equation and obtain the rigorous $W_{{\operatorname {COPW}}}$ pseudopotential definition. The explicit expressions of $W_{{\operatorname {COPW}}}$ formfactors are presented and analyzed. The peculiarities and advantages of the COPW approach in comparison with the conventional pseudopotential theory methods are discussed in detail.