The third basis set is Gaussian-type orbitals (GTOs), having been completed. The completed means that an endless number of functions must be utilised . An uncompleted or an infinite basis set can express the part of coordinate axes of MOs . Therefore, the smaller basis set is weak, providing a poor system description. It is much faster because of the determined vibrational coefficient when compared to Gaussian and others, yet it is not reciprocally orthogonal, either.