Newly emerging "electron correlation" devices made out of transition metal oxide heterostructures (Sr(Zr)TiO3), battery materials (LiMPO4 (with M = Mn, Fe, Co, and Ni) and new molecular magnets used in quantum computing are at the heart of new experimental developments in materials and chemical sciences. Such experimental progress poses many questions to our theoretical understanding. The answers can be found using a combination of modeling and theory to support the experiment. In our group, to tackle these important questions we are developing controlled, reliable, and systematically improvable theoretical methods that describe correlation effects and are able to treat solids and large molecules realistically.
Our work is interdisciplinary in nature and we connect three fields, chemistry, physics and materials science. Our goal is to develop theoretical tools that give access to directly experimentally relevant quantities. We develop and apply codes that describe two types of electronic motion (i) weakly correlated electrons originating from the delocalized "wave-like" s- and p-orbitals responsible for many electron correlation effects in molecules and solids that do not contain transition metal atoms (ii) strongly correlated electrons residing in the d- and f-orbitals that remain localized and behave "particle-like" responsible for many very interesting effects in the molecules containing d- and f-electrons (transition metal nano-particles used in catalysis, nano-devices with Kondo resonances and molecules of biological significance - active centers of metalloproteins). The mutual coupling of these two types of electronic motion is challenging to describe and currently only a few theories can properly account for both types of electronic correlation effects simultaneously.
Available research projects in the group involve (1) working on a new theory that is able to treat weakly and strongly correlated electrons in molecules with multiple transition metal centers with applications to molecular magnets and active centers of enzymes (2) developing a theory for weakly correlated electrons that is able to produce reliable values of band gaps in semiconductors and heterostructures used in solar cells industry (3) applying the QM/QM embedding theories developed in our group to catalysis on transition metal-oxide surfaces and (4) applying the embedding formalism to molecular conductance problems in order to include correlation effects.
D. Zgid, E. Gull and G. K-. L. Chan, "Dynamical mean-field theory from a quantum chemical perspective", J. Chem. Phys. , 134, 094115 (2011) (JCP Editors Choice for 2011)
D. Zgid, D. Ghosh, E. Neuscamman, and G. K-. L. Chan, "A study of cumulant approximations to n-electron valence multireference perturbation theory", J. Chem. Phys. 130, 194107 (2009)
D. Zgid and M.Nooijen, "The density matrix renormalization group self-consistent field method: Orbital optimization with the density matrix renormalization group method in the active space", J. Chem. Phys. 128, 144116 (2008)
D. Zgid and M. Nooijen, "Obtaining the two-body density matrix in the density matrix renormalization group method", J. Chem. Phys. 128, 144115 (2008)
D. Zgid and M. Nooijen, "On the spin and symmetry adaptation of the density matrix renormalization group method", J. Chem. Phys. 128, 014107 (2008)