The focus of my research is on the development and applications of computational methodologies to investigate the electronic structure of (quantum) materials in and out-of-the equilibrium. A selection of works grouped in thematic areas follows:
Spintronic and nanomagnetism
J. K. Desmarais, K. Bencheikh, G. Vignale, S. Pittalis "Exchange-correlation torques from gauge symmetries", arXiv:2506.19458 (2025)
J. K. Desmarais, A. Erba, G. Vignale, S. Pittalis "Meta-Generalized-Gradient Approximation made Magnetic", Phys. Rev. Lett. 134, 106402 (2025)
J. K. Desmarais, G. Vignale, K. Bencheikh, A. Erba, S. Pittalis "Electron localization function for non-collinear spins" Phys. Rev. Lett. 133, 136401 (2024)
J. K. Desmarais, J. Maul, B. Civalleri, A. Erba, G. Vignale, S. Pittalis "Spin-currents via the gauge-principle for meta-generalized-gradient exchange-correlation functionals" Phys. Rev. Lett. 132, 256401 (2024)
J. K. Desmarais, G. Ambrogio, G. Vignale, A. Erba, S. Pittalis "Generalized Kohn-Sham Approach for the Electronic Band Structure of Spin-Orbit Coupled Materials" Phys. Rev. Materials 8, 013802 (2024)
S. Pittalis, G. Vignale, and F.G. Eich "U(1) X SU(2) gauge invariance made simple for density functional approximations" Phys. Rev. B 96, 035141 (2017)
S. Sharma, J.K. Dewhurst, C. Ambrosch-Draxl, S. Kurth, N. Helbig, S. Pittalis, S. Shallcross, L. Nordström, and E.K.U. Gross "First-Principles Approach to Noncollinear Magnetism: Towards Spin Dynamics" Phys. Rev. Lett. 98, 196405 (2007)
Excitations
T. Gould, S.G. Dale, L. Kronik, S. Pittalis "State-specific density functionals for excited states from ensembles", Phys. Rev. Lett.134, 228001 (2025) (2025)
T. Gould and S. Pittalis "Local density approximation for excited states" Phys. Rev. X 14, 041045 (2024)
T. Gould, D. P. Kooi, P. Gori-Giorgi, S. Pittalis ''Electronic excited states in extreme limits via ensemble density functionals'' Phys. Rev. Lett. 130, 106401 (2023)
C.L. Benavides-Riveros, L. Chen, C. Schilling, S. Mantilla, S. Pittalis "Excitations of Quantum Many-Body Systems via Purified Ensembles: A Unitary-Coupled-Cluster-Based Approach" Phys. Rev. Lett. 129, 066401 (2022)
C. Schilling and S. Pittalis, "Ensemble reduced density matrix functional theory for excited states and hierarchical generalization of Pauli’s exclusion principle" Phys. Rev. Lett. 127, 023001 (2021)
T. Gould, G. Stefanucci, and S. Pittalis "Ensemble density-functional theory: Insight from the fluctuation-dissipation theorem" Phys. Rev. Lett. 125, 233001 (2020)
T. Gould and S. Pittalis "Density-Driven Correlations in Many-Electron Ensembles: Theory and Application for Excited States" Phys. Rev. Lett. 123, 016401 (2019)
T. Gould and S. Pittalis "Hartree and Exchange in Ensemble Density Functional Theory: Avoiding the Nonuniqueness Disaster" Phys. Rev. Lett. 119, 243001 (2017)
Entanglement and other measures of quantum correlations
F. Troiani, C. Angeli, A. Secchi, S. Pittalis "Genuine multipartite entanglement from many-electron systems" Letter in Phys. Rev. B 111, L161110 (2025)
F. Troiani, A. Secchi, S. Pittalis "Spins extracted from fermionic states and their entanglement properties", Phys. Rev. A 112, 012808 (2025)
S. Marocchi, S. Pittalis, and I. D'Amico "Fermionic correlations as metric distances: a useful tool for materials science" Phys. Rev. Materials 1, 043801 (2017)
S. Pittalis, F. Troiani, C.A. Rozzi, and G. Vignale "Ab-initio theory of spin-entanglement in atoms and molecules" Phys. Rev. B 91, 075109 (2015)
Time-dependent states
N. Di Palo, L. Adamska, S. Bonetti, G. Inzani, M. Talarico, M.A. Velasco, G.L. Dolso, R. Borrego-Varillas, M. Nisoli, S. Pittalis, C.A. Rozzi, and M. Lucchini "Role of crystal orientation in attosecond photoinjection dynamics of germanium" Structural Dynamics 11, 044303 (2024)
G. Inzani, L. Adamska, A. Eskandari-asl, N. Di Palo, G.L. Dolso, B. Moio, L. Jacopo D'Onofrio, A. Lamperti, A. Molle, R. Borrego-Varillas, M. Nisoli, S. Pittalis, C.A. Rozzi, A. Avella, M. Lucchini "Field-driven attosecond photoinjection dynamics in semiconductors" Nat. Photon. 17, 1059 (2023)
De Sio, E. Sommer, X.T. Nguyen, L. Groß, D. Popović, B. T. Nebgen, S. Fernandez-Alberti, S. Pittalis, C.A. Rozzi, E. Molinari, E. Mena-Osteritz, P. Bäuerle, T. Frauenheim, S. Tretiak, and C. Lienau "Intermolecular conical intersections in molecular aggregates" Nat. Nanotech. 16, 63 (2021)
S. Pittalis, A. Delgado, J. Robin, L. Freimuth, J. Christoffers, C. Lienau, and C.A. Rozzi "Charge separation dynamics and opto-electronic properties of a diaminoterephthalate-C60 dyad" Adv. Funct. Mater. 25, 2047 (2014
Systems at finite temperature
A. Sanna, S. Pittalis, J.K. Dewhurst, M. Monni, S. Sharma, G. Ummarino, S. Massidda, and E.K.U. Gross "Phononic self-energy effects and superconductivity in CaC6" Phys. Rev. B 85, 184514 (2012)
S. Pittalis, C.R. Proetto, A. Floris, A. Sanna, C. Bersier, K. Burke, and E.K.U. Gross "Exact Conditions in Finite-Temperature Density-Functional Theory" Phys. Rev. Lett. 107, 163001 (2011)
S. Massidda, F. Bernardini, C. Bersier, A. Continenza, P. Cudazzo, A. Floris, H. Glawe, M. Monni, S. Pittalis, G. Profeta, A. Sanna, S. Sharma, and E.K.U. Gross "The role of Coulomb interaction in the superconducting properties of CaC6 and H under pressure" Supercond. Sci. Technol. 22, 034006 (2009)
Low-dimensional and artificial systems
A. Guandalini, A. Ruini, E. Räsänen, C.A. Rozzi, S. Pittalis "Density-functional approach to the band gaps of finite and periodic two-dimensional systems" Phys. Rev. B 104, 085110 (2021)
A. Guandalini, C.A. Rozzi, E. Räsänen, and S. Pittalis "Fundamental gaps of quantum dots on the cheap" Phys. Rev. B 99, 125140 (2019)
E. Räsänen, C.A. Rozzi, S. Pittalis, and G. Vignale "Electron-Electron Interactions in Artificial Graphene" Phys. Rev. Lett. 108, 246803 (2012)
E. Räsänen, S. Pittalis, K. Capelle, and C.R. Proetto "Lower Bounds on the Exchange-Correlation Energy in Reduced Dimensions" Phys. Rev. Lett. 102, 206406 (2009)