The CaSiO3 triclinic crystal was studied using a quantum mechanical first principles approach. Unit cell parameters have been optimized using the local density approximation (LDA) within the density functional theory (DFT) formalism in order to minimize the total energy. A comparison was made between these theoretical results and X-ray data. We also have calculated the electronic band structure, density of states, and optical absorption. Indirect band gaps E(Q ->Gamma) = 5.43 eV and E(B ->Gamma) = 5.44 eV, and a direct gap E(Gamma ->Gamma) = 5.52 eV were obtained, as well as effective masses for electrons and holes at the maximum and minimum of valence and conduction bands, respectively. (c) 2006 Elsevier B.V. All rights reserved.