All calculations were performed with a development version of the GAUSSIAN suite of programs . Two functionals were used: the pure functional SVWN5 (called LDA in Ref. 37) and the range-separated hybrid HSE06, which has exact exchange only in the short range. Both functionals allow faster simulations for periodic systems because exact exchange is absent in the former functional and short-ranged in the latter one. A pruned (99,590) grid was used for both the energy and linear response part of the calculations for all systems. Several basis sets and k-point grids were used for different test systems, as detailed in section IV. The OR tensors were computed with the MVG and LG(OI) 2,3 schemes.