New DMFT capabilities in CASTEP

We present the first implementation of Dynamical Mean-Field Theory in UK's major ab-initio code CASTEP [1]. This implementation: i) is modular; ii) allows great flexibility in choosing local basis set for downfolding/upfolding of self-energy; iii) permits wide choice of impurity solvers (including external solver libraries); and iv) gives the user a possibility to use several self-consistency schemes and calculate total energy and forces. We explain in details the theoretical framework used. We benchmark our implementation on several strongly-correlated insulating systems with d- and f-shells: $\gamma$-Ce and Ce$_2$O$_3$ by using Hubbard I and CTHYB-QMC solvers. Our results appear to be in excellent agreement with the reference data published previously in the literature [2,3,4]. [1] E. Plekhanov, et al. in preparation (2016). [2] L. Pourovskii, et al. Phys. Rev. B 76, 235101 (2007). [3] B. Amadon, et al. Phys. Rev. B 77, 205112 (2008). [4] J. Kuneš, et al. Phys. Rev. Lett. 99, 156404 (2007).