where M is the number of GTOs used in the linear combination. N is the normalization constant and the coefficients (𝑐 𝛼 ), which are then called a linear combination of atomic orbitals (LCAO), are chosen for the shape of the basis function. There are two different ways of contracting a set of Primitive-GTOs (PGTOs) to a set of Contracted-GTOs (CGTOs), namely, segmented and general contractions. In segmented contractions, each primitive of a given atom and angular momentum is, very strictly used only in one contracted function, while in general contractions all primitives of a given atom and angular momentum are used in all the contracted functions.