Apply density-matrix TDDFT response to warm dense matter and dense plasmas

Apply an explicit one-particle density-matrix response treatment of nonlocal exchange–correlation potentials to warm dense matter and dense plasmas, where thermal excitation produces many partially occupied states, in order to assess its computational feasibility and obtain a consistent interacting response.

Background

For orbital-dependent nonlocal exchange–correlation potentials, such as hybrid and meta-GGA functionals, a formally consistent TDDFT response requires the linear response of the full off-diagonal one-particle density matrix rather than only the diagonal density response. This treatment generates the compensating contribution needed to cancel the spurious nonlocal exchange–correlation term in the first moment of the dynamic structure factor.

The paper notes that density-matrix response calculations are substantially more computationally demanding than conventional density-response TDDFT, particularly for warm dense matter and dense plasmas because thermal excitation requires a large number of partially occupied states. The authors therefore replace the unresolved direct treatment with a non-empirical dynamic exchange–correlation-kernel correction, but the explicit density-matrix approach remains unapplied to these systems.