Quantum chemistry

Our group develops new materials, as well as microscale and nanoscale functional devices literally from the bottom up. We focus on building electronic materials from molecular subunits, both organic and inorganic, using a variety of techniques to rationally design the desired properties. This encompasses chemical synthesis, characterization (both physical and chemical), combined with theoretical modeling and simulation.

Our group combines experimental and computational investigations to gain deep understanding of organic electronic materials.  The bottom line is to efficiently design novel molecular materials with improved properties.  Below are three areas we are currently studying in our lab.

1. Designer defects

2. Single-molecule piezoelectric springs

3. Organic solar cells

The Lambrecht lab develops and applys electronic structure approaches to help guide discoveries in catalysis, spectroscopy, and materials chemistry. They develop electronic structure and embedding methods that yield an accurate and computationally feasible description of chemical reactions in solvent or solid environments. In cooperation with experiment, they aim at gaining insights into the thermodynamics, kinetics and spectral signatures along catalytic pathways. Another focus is to provide rationales for the improvement of catalysts. They are working on decomposition methods that allow us to extract correlations between electronic structure descriptors for ligands and solvents and thus ultimately allow to make recommendations for more active catalyst systems. Their research areas include:

• Developing reduced-scaling first principles approaches for expedited predictions of molecular and materials properties: The aim is to enable calculations on larger systems than conventionally possible, which allows for more realistic chemical models. The scaling reduction is achieved by screening approaches exploiting the fact that some interactions between electrons (such as dispersion or vdW forces) are short-ranged and can therefore be neglected if the distance is big enough. Other approaches developed in the lab involve sparse matrix techniques, multi-scale approaches, as well as tensor decompositions.
• Energy decomposition approaches to split infrared and other spectral signatures into chemically meaningful contributions and to facilitate force field development.
• Simulating paramagnetic resonance spectra to identify the structures of metal binding sites in biological systems.
• Metal nanoparticles (optical excitation and catalysis).

The Keith group applies and develops computational chemistry to study and discover solutions to problems at the interface of engineering and basic science.  They are currently focused on modeling chemical reaction mechanisms and the atomic scale of materials to help develop renewable energy and sustainability technologies.

The group uses quantum chemistry-based multiscale modeling to predict and study the atomic scale of materials and chemical reactions. With electronic structure and atomistic methods, they can investigate fundamental reaction steps at different time- and length-scales that would otherwise be difficult or impossible to investigate with experiment. 

Notably, their studies are entirely carried out in silico (on a computer) and almost entirely free from artificial biases that are present when using experimental inputs. Whether doing so alone or in collaboration with experimentalists, the group provides deep perspective on the atomic-scale of catalytic environments to understand how they work and how to further improve them.

The 'ground-up' multiscale modeling approach uses appropriate levels of quantum chemistry (QC) theory (typically on up to ca. 200 atoms) to model reaction energies, barrier heights, pKas, and standard redox potentials. Using data obtained from QC theory, they can also develop analytic reactive forcefields, which are capable of modeling reaction dynamics on systems on the order of 100,000 atoms. Reactive forcefield data in turn can be used to generate rate constant libraries for kinetic Monte Carlo (kMC) simulations to model larger time-scale and length-scale phenomena such a nanoparticle/material growth and ripening.

Our research program is driven by significant problems in organic, biochemistry, and physical chemistry. Our research in chemical theory and computation is fully integrated in strong collaboration with successful experimental chemists. We have a full range on interests, starting with the development of fundamental ideas on the theory of chemical bonding, and how this information can be used to understand the fundamentals of Lewis acidity and basicity, organic reaction catalysis, organometallic structures, and the bonding and reactions at surfaces. In the field of biochemistry, we investigate the energetics and mechanisms of phosphoryl transfer reactions, and design new antimicrobial agents to light the increasing risk of drug resistant bacterial fungal infections.