Range separated hybrid density functional with long-range Hartree-Fock exchange applied to solids

摘要

We report a plane wave-projector augmented wave implementation of the recently proposed exchange-only range separated hybrid(RSHX)density functional [Gerber and Angyan,Chem.Phys.Lett.415,100(2005)] and characterize its performance in the local density approximation(RSHXLDA)for a set of archetypical solid state systems,as well as for some transition metal oxides.Lattice parameters,bulk moduli,band gaps,and magnetic moments of the transition metal oxides have been calculated at different values of the range separation parameter and compared with results obtained with standard local density approximation(LDA),gradient corrected(PBE),and hybrid(HSE)functionals.The RSHX functional,which has the main feature of providing a correct asymptotic behavior of the exchange potential,has a tendency to improve the description of structural parameters with respect to local and generalized gradient approximations.The band gaps are too strongly opened by the presence of the long-range Hartree-Fock exchange in all but wide-gap systems.In the difficult case of transition metal oxides,the gap is overestimated,while magnetic moments and lattice constants are slightly underestimated.The optimal range separation parameter has been found around 0.4 a.u.,slightly lower than the value of 0.5 a.u.,recommended earlier for molecular systems.