arXiv subjects

Enrico Ronca

Publications and source records attributed to Enrico Ronca.

At least 19 recordsLinked to original sources

arXiv2026

Toward a local manipulation of DNA by quantum fields

Hydrogen bonds are the fundamental backbone for deoxyribo-nucleic acid (DNA) stability. In this letter we propose a new strategy based on plasmonic cavities to perform a local manipulation of hydrogen bonds in DNA. The analysis is performed using state-of-the-art Quantum Electrodynamics Coupled Cluster calculations (QED-CC). We demonstrate that in standard strong coupling regimes, small but appreciable local modifications of the nucleotide bases' interactions can be induced in a totally non-intrusive manner. The effect can eventually be enhanced if ultra-strong coupling conditions can be reached. Our strategy provides an alternative approach to methodologies based on a collective coupling to perform optical DNA manipulation.

physics.chem-ph↗

arXiv2025

Polaritonic Bloch's Theorem beyond the Long-Wavelength Approximation

Cavity quantum electrodynamics provides a powerful tool to manipulate material properties, yet it remains a matter of debate whether and how quantized fields affect the periodicity of crystals. Here, we extend Bloch's theorem to crystals under strong light-matter coupling, revealing that polariton quasiparticles preserve lattice periodicity. We introduce a general framework to incorporate multimode cavity fields in a simple and tractable way, showing that additional modes contribute small energy corrections noticeable only at low frequencies. Within the single-photon approximation, these contributions reduce to a spatially uniform effective field in the crystal plane, providing a formal justification for the single-mode and long-wavelength approximations commonly used in molecular polaritonics. Together, these results establish a rigorous framework for describing polaritonic states in crystalline solids.

cond-mat.mtrl-sci↗

arXiv2025

eT 2.0: An efficient open-source molecular electronic structure program

The eT program is an open-source electronic structure program with emphasis on performance and modularity. As its name suggests, the program features extensive coupled cluster capabilities, performing well compared to other electronic structure programs, and, in some cases, outperforming commercial alternatives. However, eT is more than a coupled cluster program; other models based on wave function theory (such as full and reduced space configuration interaction and a variety of self-consistent field models) and density functional theory are supported. The second major release of the program, eT 2.0, has specialized functionality for strong light-matter coupling conditions. In addition, it includes a wide range of optimizations and algorithmic improvements, as well as new capabilities for exploring potential energy surfaces and for modeling experiments in the UV and X-ray regimes. Molecular gradients are now available at the coupled cluster level, and high-accuracy spectroscopic simulations are available at reduced computational cost within the multilevel coupled cluster and multiscale frameworks. We present the modifications to the program since its first major release, eT 1.0, highlighting some notable new features and demonstrating the performance of the new version relative to the first release and to other established electronic structure programs.

physics.chem-ph↗

arXiv2025

Automatic generation of density fitting auxiliary basis sets for all electron Dirac-Kohn-Sham calculations

In this study, we present a general workflow that enables the automatic generation of auxiliary density basis sets for all elements of the periodic table (from H to Og) to facilitate the general applicability of relativistic Dirac-Kohn-Sham calculations. It is an important tool for the accurate description of relativistic effects, including spin-orbit coupling, in molecules containing heavy elements. The latter are very important in various fields ranging from catalysis to quantum technologies. The automatic generation algorithm is based on an even-tempered scheme inspired by a previous work by P. Calamicini et al. J. Chem. Phys. 2007, 126, 7077, in which the auxiliary basis sets were generated for non-relativistic DFT calculations within the GGA approximation. Here, the algorithm uses basic information from the principal relativistic spinor basis set (exponents and angular momentum values) and includes a simple strategy to account for the high angular momentum of electrons in heavy and superheavy elements. The workflow developed here allows us to perform extensive automated tests aimed at verifying the accuracy of the auxiliary basis sets in a large molecular data set of about 300 molecules representing all groups and periods of the periodic table. The results show that our auxiliary basis sets achieve high accuracy, with errors in the Coulomb energies of a few {\mu}-hartree, which are of the same order of magnitude as in the non-relativistic density fitting. The automatic workflow developed here is general and will be applied in the future for optimization of auxiliary basis sets to include of exact exchange to relativistic approaches. The latter will be a crucial step for the accurate description of spectroscopic properties and the spin-dynamics in molecular systems containing heavy elements.

physics.chem-ph↗

arXiv2025

A Complete Active Space Self-Consistent Field approach for molecules in QED environments

Multireference systems are usually challenging to investigate using ab initio methods as they require an accurate description of static electron correlation. The urgency of developing similar approaches is even more pressing when molecules strongly interact with light in quantum-electrodynamics (QED) environments. In fact, in this context, multireference effects might be induced or reduced by the presence of the field. In this work, we extend the Complete Active Space Self-Consistent Field (CASSCF) approach to polaritonic systems. The method is tested on benchmark multireference problems and applied to investigate field-induced effects on the electronic structure of well-known multiconfigurational processes. Strengths and limitations of the method have been thoroughly analyzed.

physics.chem-ph↗

arXiv2025

Strong coupling quantum electrodynamics Hartree-Fock response theory

The development of reliable ab initio methods for light-matter strong coupling is necessary for a deeper understanding of molecular polaritons. The recently developed strong coupling quantum electrodynamics Hartree-Fock model (SC-QED-HF) provides cavity-consistent molecular orbitals, overcoming several difficulties related to the simpler QED-HF wave function. In this paper, we further develop this method by implementing the response theory for SC-QED-HF. We compare the derived linear response equations with the time-dependent QED-HF theory and discuss the validity of equivalence relations connecting matter and electromagnetic observables. Our results show that electron-photon correlation induces an excitation redshift compared to the time-dependent QED-HF energies, and we discuss the effect of the dipole self-energy on the ground and excited state properties with different basis sets.

physics.chem-ph↗

arXiv2025

Strong coupling M{\o}ller-Plesset perturbation theory

Perturbative approaches are methods to efficiently tackle many-body problems, offering both intuitive insights and analysis of correlation effects. However, their application to systems where light and matter are strongly coupled is non-trivial. Specifically, the definition of suitable orbitals for the zeroth-order Hamiltonian represents a significant theoretical challenge. While reviewing previously investigated orbital choices, this work presents an alternative polaritonic orbital basis suitable for the strong coupling regime. We develop a quantum electrodynamical (QED) M{\o}ller-Plesset perturbation theory using orbitals obtained from the strong coupling QED Hartree-Fock. We assess the strengths and limitations of the different approaches and emphasize the essential role of using a consistent molecular orbital framework to achieve an accurate description of cavity-induced electron-photon correlation effects.

physics.chem-ph↗

arXiv2024

Chiral polaritonics: cavity-mediated enantioselective excitation condensation

Separation of the two mirror images of a chiral molecule, the enantiomers, is a historically complicated problem of major relevance for biological systems. Since chiral molecules are optically active, it has been speculated that strong coupling to circularly polarized fields may be used as a general procedure to unlock enantiospecific reactions. In this work, we focus on how chiral cavities can be used to drive asymmetry in the photochemistry of chiral molecular systems. We first show that strong coupling to circularly polarized fields leads to enantiospecific Rabi splittings, an effect that displays a collective behavior in line with other strong coupling phenomena. Additionally, entanglement with circularly polarized light generates an asymmetry in the enantiomer population of the polaritons, leading to a condensation of the excitation on a preferred molecular configuration. These results confirm that chiral cavities represent a tantalizing opportunity to drive asymmetric photochemistry in enantiomeric mixtures.

physics.chem-ph↗

arXiv2024

A comprehensive theory for relativistic polaritonic chemistry: a four components ab initio treatment of molecular systems coupled to quantum fields

We present a new ab initio approach to study molecules containing heavy atoms strongly interacting with quantum fields in optical devices. The theory has been derived from the relativistic quantum electrodynamics (QED) introducing the approximations needed to provide a formalism suitable for relativistic quantum chemistry. This framework represents the ideal starting point to extend the main quantum chemistry methods to relativistic polaritonic. The Polaritonic Dirac Hartree Fock (Pol-DHF) approach is the first method we propose based on this theory. Pol-DHF allows for the simulation of field induced effects on the ground and excited state properties of heavy transition metals molecular complexes. The method is able to include not only the effects of the photons, but can in principle be extended also to include explicit interactions with positrons. Application of Pol-DHF to three metal hydrides shows that the magnitude of both polaritonic and relativistic effects can be comparable when relativistic effects are getting more important. Due to an accurate description of spin-orbit coupling, the method is able to reproduce polaritonic effects happening at the crossing between singlet and triplet potential energy surfaces.

physics.chem-ph↗

arXiv2024

Strong coupling electron-photon dynamics: a real-time investigation of energy redistribution in molecular polaritons

We analyze the real-time electron-photon dynamics in long-range polariton-mediated energy transfer using a real-time quantum electrodynamics coupled cluster (RT-QED-CC) model, which allows for spatial and temporal visualization of transport processes. We compute the time evolution of photonic and molecular observables, such as the dipole moment and the photon coordinate, following the excitation of the system induced by short laser pulses. Our simulation highlights the different time scales of electrons and photons under light-matter strong coupling, the role of dark states, and the differences with the electronic (F\"orster and Dexter) energy exchange mechanisms. The developed method can simulate multiple high-intensity laser pulses while explicitly retaining electronic and electron-photon correlation and is thus suited for nonlinear optics and transient absorption spectroscopies of molecular polaritons.

physics.chem-ph↗

arXiv2024

Theory of magnetic properties in QED environments: application to molecular aromaticity

In this work, we present ab initio cavity QED methods which include interactions with a static magnetic field and nuclear spin degrees of freedom using different treatments of the quantum electromagnetic field. We derive explicit expressions for QED-HF magnetizability, nuclear shielding, and spin-spin coupling tensors. We apply this theory to explore the influence of the cavity field on the magnetizability of saturated, unsaturated, and aromatic hydrocarbons, showing the effects of different polarization orientations and coupling strengths. We also examine how the cavity affects aromaticity descriptors, such as the nucleus-independent chemical shift and magnetizability exaltation. We employ these descriptors to study the trimerization reaction of acetylene to benzene. We show how the optical cavity induces modifications in the aromatic character of the transition state leading to variations in the activation energy of the reaction. Our findings shed light on the effects induced by the cavity on magnetic properties, especially in the context of aromatic molecules, providing valuable insights into understanding the interplay between the quantum electromagnetic field and molecules.

physics.chem-ph↗

arXiv2023

Collective Strong Coupling Modifies Aggregation and Solvation

Intermolecular interactions are pivotal for aggregation, solvation, and crystallization. We demonstrate that the collective strong coupling of several molecules to a single optical mode results in notable changes in the molecular excitations around an impurity, e.g., in the first aggregation or solvation shell. A competition between short-range Coulombic and long-range photonic correlation inverts the local transition density in a polaritonic state, suggesting notable changes in the polarizability of the solvation shell. Our results provide an alternative perspective on recent work in polaritonic chemistry and pave the way for the rigorous treatment of cooperative effects in aggregation, solvation, and crystallization.

quant-ph↗

arXiv2023

Coupled cluster cavity Born-Oppenheimer approximation for electronic strong coupling

Chemical and photochemical reactivity, as well as supramolecular organization and several other molecular properties, can be modified by strong interactions between light and matter. Theoretical studies of these phenomena require the separation of the Schr\"odinger equation into different degrees of freedom as in the Born-Oppenheimer approximation. In this paper, we analyze the electron-photon Hamiltonian within the cavity Born-Oppenheimer approximation (CBOA), where the electronic problem is solved for fixed nuclear positions and photonic parameters. Specifically, we focus on intermolecular interactions in representative dimer complexes. The CBOA potential energy surfaces are compared with those obtained using a polaritonic approach, where the photonic and electronic degrees of freedom are treated at the same level. This allows us to assess the role of electron-photon correlation and the accuracy of CBOA.

physics.chem-ph↗

arXiv2023

Strong coupling to circularly polarized photons: towards field-induced enantioselectivity

The development of new methodologies for the selective synthesis of individual enantiomers is still one of the major challenges in synthetic chemistry. Many biomolecules, and therefore many pharmaceutical compounds, are indeed chiral. While the use of chiral reactants or catalysts has led to significant progress in the field of asymmetric synthesis, a systematic approach applicable to general reactions has still not been proposed. In this work, we show that strong coupling to circularly polarized fields represents a promising alternative for reaching highly selective asymmetric synthesis in a non-invasive fashion. We demonstrate that the field induces stereoselectivity in the early stages of the chemical reaction, by selecting an energetically preferred direction of approach for the reagents.

physics.chem-ph↗

arXiv2023

Two-Dimensional Moir\'e Polaronic Electron Crystals

Two-dimensional moir\'e materials have emerged as the most versatile platforms for realizing quantum phases of electrons. Here, we explore the stability origins of correlated states in WSe2/WS2 moir\'e superlattices. We find that ultrafast electronic excitation leads to melting of the Mott states on time scales five times longer than predictions from the charge hopping integrals and the melting rates are thermally activated, with activation energies of 18 and 13 meV for the one- and two-hole Mott states, respectively, suggesting significant electron-phonon coupling. DFT calculation of the one-hole Mott state confirms polaron formation and yields a hole-polaron binding energy of 16 meV. These findings reveal a close interplay of electron-electron and electron-phonon interactions in stabilizing the polaronic Mott insulators at transition metal dichalcogenide moir\'e interfaces.

cond-mat.str-el↗

arXiv2023

Polaritonic response theory for exact and approximate wave functions

Polaritonic chemistry is an interdisciplinary emerging field that presents several challenges and opportunities in chemistry, physics, and engineering. A systematic review of polaritonic response theory is presented, following a chemical perspective based on molecular response theory. We provide the reader with a general strategy for developing response theory for ab initio cavity quantum electrodynamics (QED) methods and critically emphasize details that still need clarification and require cooperation between the physical and chemistry communities. We show that several well-established results can be applied to strong coupling light-matter systems, leading to novel perspectives on the computation of matter and photonic properties. The application of the Pauli-Fierz Hamiltonian to polaritons is discussed, focusing on the effects of describing operators in different mathematical representations. We thoroughly examine the most common approximations employed in ab initio QED, such as the dipole approximation. We introduce the polaritonic response equations for recently developed ab initio QED Hartree-Fock and QED coupled cluster methods. The discussion focuses on the similarities and differences from standard quantum chemistry methods, providing practical equations for computing the polaritonic properties.

physics.chem-ph↗

arXiv2023

Effective single mode methodology for strongly coupled multimode molecular-plasmon nanosystems

Strong coupling between molecules and quantized fields has emerged as an effective methodology to engineer molecular properties. New hybrid states are formed when molecules interact with quantized fields. Since the properties of these states can be modulated by fine-tuning the field features, an exciting and new side of chemistry can be explored. In particular, significant modifications of the molecular properties can be achieved in plasmonic nanocavities, where the field quantization volume is reduced to sub-nanometric volumes. Intriguing applications of nanoplasmonics include the possibility of coupling the plasmons with a single molecule, instrumental for sensing, high-resolution spectroscopy, and single-molecule imaging. In this work, we focus on phenomena where the simultaneous effects of multiple plasmonic modes are critical. We propose a theoretical methodology to account for many plasmonic modes simultaneously while retaining computational feasibility. Our approach is conceptually simple and allows us to accurately account for the multimode effects and rationalize the nature of the interaction between multiple plasmonic excitations and molecules.

physics.chem-ph↗

arXiv2022

Molecular van der Waals fluids in cavity quantum electrodynamics

Intermolecular van der Waals interactions are central to chemical and physical phenomena ranging from biomolecule binding to soft-matter phase transitions. However, there are currently very limited approaches to manipulate van der Waals interactions. In this work, we demonstrate that strong light-matter coupling can be used to tune van der Waals interactions, and, thus, control the thermodynamic properties of many-molecule systems. Our analyses reveal orientation dependent single molecule energies and interaction energies for van der Waals molecules (for example, H$_{2}$). For example, we find intermolecular interactions that depend on the distance between the molecules $R$ as $R^{-3}$ and $R^{0}$. Moreover, we employ non-perturbative \textit{ab initio} cavity quantum electrodynamics calculations to develop machine learning-based interaction potentials for molecules inside optical cavities. By simulating systems ranging from $12$ H$_2$ to $144$ H$_2$ molecules, we demonstrate that strong light-matter coupling can tune the structural and thermodynamic properties of molecular fluids. In particular, we observe varying degrees of orientational order as a consequence of cavity-modified interactions, and we explain how quantum nuclear effects, light-matter coupling strengths, number of cavity modes, molecular anisotropies, and system size all impact the extent of orientational order. These simulations and analyses demonstrate both local and collective effects induced by strong light-matter coupling and open new paths for controlling the properties of molecular clusters.

physics.chem-ph↗