• Third-order energy derivative corrections to the Kohn-Sham orbital hardness tensor

    • Fulltext

       

        Click here to view fulltext PDF


      Permanent link:
      https://www.ias.ac.in/article/fulltext/jcsc/117/05/0485-0490

    • Keywords

       

      Orbital hardness tensor; DFT; third-order energy derivatives; Janak’s theorem

    • Abstract

       

      The third term in the Taylor expansion of the total energy functional around the number of electronsN is evaluated as the second-order derivative of orbital Kohn-Sham energies with respect to orbital occupancy. Present approach is an extension of an efficient algorithm to compute densityfunctional based orbital reactivity indices. Various energy derivatives used to approximate orbital reactivity indices are defined within the space spanned by the orbital occupation numbers and the Kohn-Sham one-electron energies. The third-order energy functional derivative has to be considered for singular hardness tensor ([η]). On the contrary, this term has negligible influence on the reactivity index values for atomic or molecular systems with positively defined hardness tensors. In this context, stability of a system in equilibrium state estimated through the eigenvalues of [η] is discussed. Numerical illustration of the Kohn-Sham energy functional derivatives in orbital resolution up to the third order is shown for benchmark molecules such as H2O, H2S, and OH.

    • Author Affiliations

       

      Tzonka Mineva1

      1. Institute of Catalysis, Bulgarian Academy of Science (BAS), G. Bonchev Str. 11, 1113-Sofia, Bulgaria
    • Dates

       
  • Journal of Chemical Sciences | News

© 2021-2022 Indian Academy of Sciences, Bengaluru.