Abstract

Density matrix renormalization group (DMRG) is a method that is capable of describing strongly correlated quantum systems. In this talk I will give a brief pedagogical overview of the method along with recent technical advances that have allowed DMRG to treat challenging chemistry of metalloenzymes on the one end and the ultra high accuracy energetics of small molecules on the other end.

The power of DMRG will be demonstrated by studying the chemistry of the Fe2S2 and Fe4S4 clusters that are ubiquitous biological motifs performing electron transfer and storage in biological processes ranging from photosynthesis and nitrogen fixation. All previous attempts to study these clusters, both theoretically and experimentally, had assumed the validity of empirical models like the Anderson’s Heisenberg-Double-Exchange hamiltonian (HDE) that had so far remained untested. By directly calculating over hundred low lying states for these clusters ab-initio without any model assumptions, it was shown that the simple HDE model was qualitatively incorrect and underestimates the number of low-lying states by an order of magnitude.