Theoretical and Computational Chemistry and Materials Science
  Electronic structure methods and calculations on free molecules, molecules in confined space, molecules adsorbed on surfaces, clusters, and nano-hybrids, with emphasis on excited electronic states and processes
  Computer-aided design of carbon-based nanomaterials and hybrid open framework structures
  Theoretical Methods for the calculation of electronic, structural, vibrational and optical properties of materials
  Theoretical Inorganic and Organometallic Chemistry
  Theoretical and Numerical Methods for Photonics, Optoelectronics and Metamaterials
  Molecular Simulations of Polymer-based and Bio-based Nanostructured Systems

Theoretical and Computational Chemistry and Materials Science

Development of the reduced density matrix functional theory and constrained effective local potentials
Dr. Nektarios Lathiotakis, Research Director
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A main direction of our research focuses on the foundations of the reduced density matrix functional theory (RDMFT). An alternative to DFT theory, RDMFT is an approach to the problem of electronic correlations aiming to offer an improved description of static correlations. Our group has made significant contribution in the application of RDMFT to periodic systems. More specifically we contributed to the development of new functionals, like the so-called Power functional and their implementation/assessment for molecular and periodic systems. Interestingly, such approximations were found describe well the fundamental gaps of transition metal oxides, a promising result towards the construction of a scheme to study strongly correlated systems. We have also considered the enforcement of the generalized Pauli constraints in RDMFT aiming to remedy inaccuracies of present functionals when applied to spin-systems.  In addition, we proposed necessary conditions for the one-body reduced density matrix (1RDM) for the description of triplet states and studied consequences of the generalized Pauli constraints in the structure of the 1RDM. Finally, we have introduced quantitative criteria for the distinction of static and dynamic electronic correlations in many electron systems.

A serious issue in Kohn-Sham DFT is the actual value of the single particle Kohn-Sham (KS) orbitals and their corresponding energy eigenvalues. In order to improve the quality of the local KS potential, we proposed to replace it with the optimal one that respects certain subsidiary conditions that enforce exact properties, like, for instance, the correct asymptotic behavior of the potential. This method is applicable to any density functional approximation and offers a significant improvement in the local potential resulting in better single particle spectrum. We applied the same recipe together with RDMFT functionals (local RDMFT), thus combining the non-idempotency of RDMFT with a KS-like local potential, a combination that potentially offers improved single particle spectral properties and decent description of static correlations at the same time despite the fact that the natural orbitals in RDMFT cannot be obtained by a local potential. In addition, we proposed a method to invert any given density in order to obtain the corresponding constrained local potential with predefined asymptotic behavior and demonstrated its efficiency and quality of the resulting potentials. Finally, based on the improvement of the constrained local potential method, we are working on hybrid schemes that further improve the spectral properties.


Key publications

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J. Chem. Phys. 2014, 141, 164120

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J. Chem. Theory Comput. 2015, 11, 4895


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J. Chem. Theory Comput. 2016, 12, 2668

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Phys. Chem. Chem. Phys. 2017, 19, 12655


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J. Chem. Phys. 2020, 152, 164114



Recent publications (since 2013)






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