Reply to comment on "Relativistic all-electron Hartree-Fock-Dirac calculation of a quasi one-dimensional chain of selenium atoms''

We have calculated the energy band structure of a linear model chain of sel enium atoms on the basis of the ab initio four-component Hartree-Fock-Dirac equations to verify that the MOLFDIR program, extended for periodic polyme rs, is working well. The comparative calculation using the same relativisti c basis set at the non-relativistic Hartree-Fock crystal orbital level show s that both results are similar, because the relativistic effects are expec ted to be small. Contrary to the finding of Schmidt and Springborg, we are convinced that poly(Se) is not a metal but an insulator. Additional evidenc e has been obtained from non-relativistic calculations with different basis sets. Their results may be an artefact of the density functional approach. We agree, that our relativistic basis set is not large enough to give the correct size of the band gap. (C) 2000 Published by Elsevier Science B.V. A ll rights reserved.