17.2.5 Rangehybrid methods (RANGEHYBRID)

For coupling of short-range (sr-)DFT with long-range (lr-)ab-initio methods, one first has to specify the coupling parameter $\mu$ in the sr interelectronic interaction $\sum_{i<j} {\rm erf} (\mu r_{ij})/r_{ij}$; this can be done by setting a variable (e.g. mu=0.5). As a next step, long-range ERIs have to be calculated by calling the integral program (e.g. int;erf,mu;).

Then sr-DFT/lr-HF calculations can be performed by calling the RKS program with the additional subcommand rangehybrid. Available short-range functionals are exerf and ecerf for sr-LDA, and exerfpbe and ecerfpbe for sr-PBE; as usual, the functionals have to be specified after the rks command (e.g. rks,exerf,ecerf;). The underlying short-range LDA correlation functional is that of S. Paziani, S. Moroni, P. Gori-Giorgi, G.B. Bachelet, Phys. Rev. B 73, 155111 (2006).

Finally, sr-DFT/lr-post-HF calculations can be done by adding, within a call of the chosen post-HF program, two subcommands: srxcdft followed by the desired short-range functionals (e.g. srxcdft,exerf,ecerf;), and dftden followed by the record number from which the density for the sr functionals is taken. Implementations are available for ci, mp2, ccsd, ccsd(t), and the corresponding local MP2 and CC methods w/wo density-fitting.

molpro@molpro.net 2019-03-22