We calculate lattice thermal conductivities in the reciprocal space using Boltzmann transport formalism and perturbation theory to phonon-phonon scattering. We limit ourselves to three-phonon scattering for two reasons. First, the four-phonon scattering calculation is too demanding to be carried out at a large scale, which is our ultimate objective. Second, three-phonon scattering is sufficiently accurate in most cases , and even when its accuracy becomes insufficient, e.g. for highly anharmonic materials with very low LTC and strong 4th-order interaction, it is still sufficient for predicting qualitatively very low LTC for those materials . These materials, not many in the grand scheme of things, can be subject to deeper, targeted studies involving four-phonon scattering once identified.