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Dr Nikitas Gidopoulos' Outputs (25)

Calculation of electronic excited states of molecules using the Helmholtz free-energy minimum principle (2013)
Journal Article
Pastorczak, E., Gidopoulos, N., & Pernal, K. (2013). Calculation of electronic excited states of molecules using the Helmholtz free-energy minimum principle. Physical Review A, 87(6), Article 062501. https://doi.org/10.1103/physreva.87.062501

We show that the Helmholtz free-energy variational principle is the physical principle underlying the ensemble variational theory formulated in seminal papers by Theophilou and by Gross, Oliveira, and Kohn. A method of calculating electronic excitati... Read More about Calculation of electronic excited states of molecules using the Helmholtz free-energy minimum principle.

Parametric representation of open quantum systems and cross-over from quantum to classical environment (2013)
Journal Article
Calvani, D., Cuccoli, A., Gidopoulos, N., & Verrucchi, P. (2013). Parametric representation of open quantum systems and cross-over from quantum to classical environment. Proceedings of the National Academy of Sciences, 110(17), 6748-6753. https://doi.org/10.1073/pnas.1217776110

The behavior of most physical systems is affected by their natural surroundings. A quantum system with an environment is referred to as open, and its study varies according to the classical or quantum description adopted for the environment. We propo... Read More about Parametric representation of open quantum systems and cross-over from quantum to classical environment.

Constraining density functional approximations to yield self-interaction free potentials (2012)
Journal Article
Gidopoulos, N., & Lathiotakis, N. (2012). Constraining density functional approximations to yield self-interaction free potentials. The Journal of Chemical Physics, 136(22), Article 224109. https://doi.org/10.1063/1.4728156

Self-interactions (SIs) are a major problem in density functional approximations and the source of serious divergence from experimental results. Here, we propose to optimize density functional total energies in terms of the effective local potential,... Read More about Constraining density functional approximations to yield self-interaction free potentials.

Nonanalyticity of the optimized effective potential with finite basis sets (2012)
Journal Article
Gidopoulos, N., & Lathiotakis, N. (2012). Nonanalyticity of the optimized effective potential with finite basis sets. Physical Review A, 85(5), Article 052508. https://doi.org/10.1103/physreva.85.052508

We show that the finite-basis optimized effective potential (OEP) equations exhibit previously unknown singular behavior. Imposing continuity, we derive new well-behaved finite-basis-set OEP equations that determine OEP for any orbital and any large... Read More about Nonanalyticity of the optimized effective potential with finite basis sets.