First principles calculations of structural, electronic and optical properties of various phases of CaS A. Shaukat, Y. Saeed, N. Ikram and H. Akbarzadeh Eur. Phys. J. B, 62 4 (2008) 439-446 Published online: 22 May 2008 DOI: 10.1140/epjb/e2008-00193-x