PNNL

The Science

When molecules are confined in optical cavities and strongly coupled to quantized electromagnetic fields, their properties can be modified in ways that require electronic structure approaches to predict these changes. Accurate modeling of these systems requires methods that treat electronic and photonic degrees of freedom on equal footing. In a series of publications, researchers detailed the development of several advances in quantum electrodynamical electronic structure methods for strongly coupled light–matter systems. These approaches improve the accuracy of ground-state and polariton potential energy surfaces, provide a consistent description of electron–photon interactions, and enable scalable simulations on leadership-class computing facilities.

The Impact

Confinement within optical cavities modifies molecular energetics and reshapes chemical landscapes, creating opportunities to control reactivity. Realizing this potential requires rigorous theoretical frameworks that extend beyond conventional electronic structure theory. This body of work advances the field toward accurate and computationally feasible simulations of cavity-modified systems and establishes a foundation for the predictive design of ground- and excited-state processes under strong light–matter coupling.

Summary

Cavity-modified chemistry explores how strong coupling to confined electromagnetic fields alters chemical behavior. Researchers developed a hierarchy of complementary theoretical approaches spanning multiple levels of electronic structure theory to address these types of systems.

At the density functional level, a meta generalized gradient approximation was introduced to capture cavity-dependent exchange–correlation interactions, improving dispersion coefficients and energetics within quantum electrodynamical density functional theory. At the multireference level, a state averaged cavity quantum electrodynamics complete active space self-consistent field (QED-CASSCF) method was developed to describe correlated electronic and photonic degrees of freedom, enabling accurate ground- and excited-state polariton potential energy surfaces. At the coupled cluster level, a scalable quantum electrodynamics coupled cluster (QED-CC) implementation extended high-accuracy correlated wavefunction methods to complex cavity-modified systems.

Because incorporating quantum electrodynamical effects increases computational cost, efficient high-performance implementations are essential. The team developed a graphics processing unit-enabled, open-source implementation of QED-CC within the ExaChem program package, leveraging distributed memory parallelism and tensor contraction frameworks to achieve scalable performance across heterogeneous architectures.

Together, these advances establish a systematically improvable framework for modeling ground- and excited-state chemistry under strong light–matter coupling.

Contact

Niri Govind, Pacific Northwest National Laboratory, niri.govind@pnnl.gov 

Funding

The authors acknowledge support from the Center for Many-Body Methods, Spectroscopies, and Dynamics for Molecular Polaritonic Systems (MAPOL) under FWP 79715. This support is part of the Computational Chemical Sciences program funded by the Department of Energy (DOE), Office of Science, Basic Energy Sciences program, Division of Chemical Sciences, Geosciences, and Biosciences. This research acknowledges the resources of the Argonne Leadership Computing Facility at Argonne National Laboratory, which is supported by the U.S. DOE, Office of Science, under contract number DE-AC02-06CH11357. This work also benefited from computational resources provided by the National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science user facility operated under Contract No. DE-AC02-05CH11231.