Academic Commons

Theses Doctoral

Predicting the temperature-strain phase diagram of VO$_2$ from first principles

Kim, Chanul

Predicting the temperature-strain phase diagram of VO$_2$, 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 VO$_2$, we build a minimal model of the structural energetics using the Peirels-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 VO$_2$ is better described as a Mott assisted Peierls transition.

Files

This item is currently under embargo. It will be available starting 2020-05-02.

More About This Work

Academic Units
Applied Physics and Applied Mathematics
Thesis Advisors
Marianetti, Chris A.
Degree
Ph.D., Columbia University
Published Here
May 14, 2018
Academic Commons provides global access to research and scholarship produced at Columbia University, Barnard College, Teachers College, Union Theological Seminary and Jewish Theological Seminary. Academic Commons is managed by the Columbia University Libraries.