Séminaire de Maurizio Rodríguez-Mayorga (Institut Néel Grenoble)

Séminaire de Maurizio Rodríguez-Mayorga (Institut Néel Grenoble)

Two branches of the same tree, the dynamic and non-dynamic electronic correlation problem.

M. Rodríguez-Mayorga, P. Besalú-Sala, A. J. Pérez-Jiménez, J. C. Sancho-García, F. Bruneval, K.J.H. Giesbertz, L. Visscher

The search for methods able to account for accurate electronic correlation energies is probably one of the major goals of quantum chemists/physicists. Electronic correlation effects are usually classified as dynamic or non-dynamic, which has serve as yardstick to design methods to account for either dynamic or non-dynamic correlation energies. In this talk, we present the extensions of the applicability of the random phase approximation (RPA) and of reduced density matrix functional theory (RDMFT) approximations, which are methods designed to account for dynamic and non-dynamic correlation effects, respectively.

On the one hand, methods based on many-body perturbation theory (like RPA) have shown to be reliable to compute dynamic correlation energies with a low computational cost[1]. Therefore, in this talk, we show that the RPA is a perfect candidate to compute static non-linear optical properties[2] in systems dominated by dynamic correlation effects, where the workhorse of computational chemists/physicists (density functional theory  [DFT]) usually fails dramatically.

On the other hand, the applicability of reduced density matrix functional theory (RDMFT) is increasing among the chemists and physicist communities (see for example Refs. 3-5) due to its ability to account for non-dynamic electronic correlation effects. To further extend RDMFT applicability, we introduce in this work its relativistic version. Relativistic RDMFT[6] is presented using the Dirac 4-component Hamiltonian and considering the so-called no-pair approximation[7], which allows us to present the relativistic version of some of the most accurate RDMFT functional approximations[4,5]. Finally, we analyze some properties of these functional approximations.

Bibliography
1.- Rojas, H. N.; Godby, R. W.; Needs, R. J. (1995) Space-Time Method for Ab Initio Calculations of Self-Energies and Dielectric Response Functions of Solids. Phys. Rev. Lett., 74, 1827.
2.- Besalú-Sala, P., Bruneval, F., Pérez-Jiménez, Á. J., Sancho-García, J. C., & Rodríguez-Mayorga, M. (2023). RPA, an Accurate and Fast Method for the Computation of Static Nonlinear Optical Properties. J. Chem. Theory Comput., 19, 6062.
3.- Piris, M. (2013). Interpair electron correlation by second-order perturbative corrections to PNOF5. J. Chem. Phys., 139, 064111.
4.- Piris, M. (2017). Global method for electron correlation. Phys. Rev. Lett., 119, 063002.
5.- Lemke, Y., Kussmann, J., & Ochsenfeld, C. (2022). Efficient integral-direct methods for self-consistent reduced density matrix functional theory calculations on central and graphics processing units. J. Chem. Theory Comput., 18, 4229.
6- Rodríguez-Mayorga, M., Giesbertz, K.J.H., & Visscher. L. (2022). Relativistic reduced density matrix functional theory. SciPost Chemistry. 1, 004.