anchor.diff:  { lib, stdenv, fetchFromGitHub, python3, gfortran, blas, lapack
   , fftw, libint, libvori, libxc, mpi, gsl, scalapack, openssh, makeWrapper
  -, libxsmm, spglib, which, elpa, pkg-config
  +, libxsmm, spglib, which, pkg-config
  +, enableElpa ? false
  +, elpa
   } :
   
   let
  
positive.code:     scalapack
      blas
      lapack
    ];
  
    propagatedBuildInputs = [ mpi ];
    propagatedUserEnvPkgs = [ mpi ];
  
negative.code: 
    nativeBuildInputs = [ python3 which openssh makeWrapper pkg-config ];
    buildInputs = [
      gfortran
      fftw
      gsl
  