seminar | CRC 1639 NuMeriQS

Computational Astrochemistry

Tue, 16 Dec 2025 15:15:00 +0000

Serena Viti will talk on

Computational Astrochemistry

In Astrochemsitry - the field that studies molecules in space - building accurate chemical models is central to our understanding of how molecules can form and be destroyed in space. The accuracy of such models however is heavily dependent on the availability of complete chemical gas-phase and solid-state reaction networks. Due to the very non linear nature of chemistry in space, as well as the complex interactions between the chemistry and the physics of the gas and dust, determining the right sets of species and possible reactions between them is not trivial. In this talk I shall give an overview of the challenges we face when designing and optimizing networks as well as possible avenues for solutions, including sensitivity analysis, data-driven methods and machine learning.

Promit Ray’s title is

Smarter Molecules, Safer Models: A Virtual Chemistry AI Lab for Governed Scientific Discovery

AI now plays a central role in proposing new molecules, optimizing materials, and accelerating numerical modeling, yet its scientific reliability ultimately depends on the structure and integrity of the underlying data. In this talk, I present a practical end-to-end workflow that integrates Vivian for interactive molecular and materials exploration, ChemLabFlow for standardized chemical and experimental data management, and the VAIL (Virtual AI Lab) as a governed

Infinite Matrix Product States for (1+1)-Dimensional Gauge Theories

Mon, 15 Dec 2025 17:15:00 +0000

(1+1)-dimensional gauge theories provide tractable toy models for studying non-perturbative phenomena of importance in (3+1)-dimensional field theories such as QCD. In the past decade, tensor network methods have enabled new lattice studies of such theories in the Hamiltonian formalism. However, existing approaches have been limited in their ability to maintain manifest translation invariance and locality for non-abelian theories. In this talk, we present link-enhanced matrix product operators (LEMPOs), a novel construction that acts on both the physical and virtual spaces of symmetric matrix product states. LEMPOs allow us to represent the lattice Hamiltonians of (abelian or non-abelian) gauge theories in a local and manifestly translation-invariant form, enabling studies on infinite lattices. We demonstrate this method with recent results for the Schwinger model and adjoint QCD2.

Projected Entangled Pair States for Lattice Gauge Theories with Dynamical Fermions

Tue, 09 Dec 2025 15:15:00 +0000

Gauge theories underpin much of modern physics, from the Standard Model to effective descriptions of strongly interacting systems. While quantum chromodynamics is perturbative at high energies, nonperturbative tools are required in the low-energy regime. Lattice gauge theory provides a gauge-invariant regularization well suited for this purpose. By using Euclidean Monte Carlo simulations, this formulation has enabled major progress. Yet important regimes — such as finite-density fermionic systems and real-time dynamics — remain difficult due to the sign problem and the Euclidean nature of standard algorithms. These challenges have motivated alternative approaches, including Hamiltonian formulations amenable to quantum simulation and variational methods. Among the most powerful classical variational techniques are tensor networks. In this talk, I will give a short introduction into tensor networks and introduce a specific Ansatz, Gauged Gaussian Projected Entangled Pair States (GGPEPS). GGPEPS are gauge-invariant tensor-network, that allow efficient contraction in higher spatial dimension, and avoid the sign problem due to a variational Monte Carlo procedure. I will outline their construction, discuss key analytical features, and demonstrate their numerical performance on a (2+1)d Z2 lattice gauge theory with dynamical fermionic matter.

Floquet physics and Lattice fermions

Fri, 13 Dec 2024 13:15:00 +0000

t.b.a.

Wed, 11 Dec 2024 14:15:00 +0000

The convergence of HMC on non-compact Riemannian Manifolds

Tue, 16 Apr 2024 15:15:00 +0000