CRYSTAL is a quantum chemistry ab initio program, designed primarily for calculations on crystals (3 dimensions), slabs (2 dimensions) and polymers (1 dimension) using translational symmetry, but it can be used for single molecules. Quantum chemistry is a branch of Theoretical chemistry, which applies Quantum mechanics and Quantum field theory to address issues and problems in Ab initio quantum chemistry methods are Computational chemistry methods based on Quantum chemistry. [1] It is written by V. R. Saunders, R. Dovesi, C. Roetti, R. Orlando, C. M. Zicovich-Wilson, N. M. Harrison, K. Doll, B. Civalleri, I. J. Bush, Ph. D’Arco, and M. Llunell from Theoretical Chemistry Group at the University of Torino and the Computational Materials Science Group at the Daresbury Laboratory near Warrington in Cheshire, England. The University of Turin ( Italian Università degli Studi di Torino, UNITO is a University in the city of Turin in the Piedmont region Daresbury Laboratory is a scientific research laboratory near Daresbury in Cheshire, England, which began operations in 1962 and was officially opened on Warrington is a large town borough and Unitary authority area in Cheshire, England. Cheshire (or archaically the County of Chester) is a county in North West England. England is a Country which is part of the United Kingdom. Its inhabitants account for more than 83% of the total UK population whilst its mainland The current version is CRYSTAL06. Earlier versions were CRYSTAL88, CRYSTAL92, CRYSTAL95, CRYSTAL98 and CRYSTAL03.