BioPhysics and Condensed Matter Seminar: Dr. Chanul Kim, Columbia University  Add To Calendar

  • Date(s): Thursday, 5/10 2:00 PM to Thursday, 5/10 3:00 PM
  • Speaker: Dr. Chanul Kim
  • Host: Prof. Hyowon Park
  • Campus Address: 2214 SES
Title: Predicting the Temperature-strain Phase Diagram of VO2 from First Principles

Abstract: Predicting the temperature-strain phase diagram of VO2, including the various structural allotropes, from first principles is a grand challenge of materials physics, and even the phase diagram remains unclear at T = 0K. The coexistence of Peierls and Mott physics suggests that a theory which can capture strong electronic correlations will be necessary to compute the total energies. In order to understand the complex nature of the first-order transition of VO2, we build a minimal model of the structural energetics using the Peierls-Hubbard model and solve it exactly using the Density Matrix Renormalization Group (DMRG) methods demonstrating that the on-site interaction U has a minimal effect on the structural energetics for physical parameters. These results explain the qualitative failures of Density Functional Theory (DFT) and DFT+U for the structural energetics, in addition to the partial success of the unorthodox DFT+U results (i.e. non-spin-polarized and small U). It also guides the creation of empirical corrections to the DFT+U functional which allow us to semi-quantitatively capture the phase stability of the rutile and monoclinic phases as a function of temperature and strain. Our work demonstrates that VO2 is better described as a Mott assisted Peierls transition.

Cm-Bio 5-10 Kim flyer