  The Douglas-Kroll transformed Dirac-Coulomb Hamiltonian is used to describe
scalar-relativistic effects in solids. A Hartree-Fock approximation with
periodic boundary conditions makes it feasible to use methods originally
developed for atoms and molecules to solve the corresponding equations for
crystalline systems. The implementation is realized within the CRYSTAL program.
Scalar-relativistic effects in silver compounds of FCC structure such as AgF,
AgCl, AgBr and Ag are investigated for the molar formation energy, the lattice
parameter, the isothermal bulk modulus and the pressure derivative.
