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publications

How large are nonadiabatic effects in atomic and diatomic systems?

Published in The Journal of Chemical Physics, 2015

We simulated small (<10 e) atoms and molecules in their ground states, treating the electrons and ions on the same footing, i.e. without invoking the Born-Oppenheimer approximation.

Recommended citation: Y. Yang, I. Kylänpää, N. M. Tubman, J. T. Krogel, S. Hammes-Schiffer, and D. M. Ceperley, "How large are nonadiabatic effects in atomic and diatomic systems?, " J. Chem. Phys. 143, 124308 (2015). https://aip.scitation.org/doi/10.1063/1.4931667

Electronic band gaps from Quantum Monte Carlo methods

Published in arXiv, 2019

We prove the leading-order scaling of the fundamental gap based on the asymptotic behavior of changes in the electronic structure factor S(k) in the long wavelength limit (k=0). We further directly calculate finite-size correction to leading and sub-leading orders using only S(k) at one system size.

Recommended citation: Y. Yang, V. Gorelov, C. Pierleoni, D. M. Ceperley, and M. Holzmann, "Electronic band gaps from Quantum Monte Carlo methods, " arXiv: 1910.07531

Quantum Monte Carlo Compton profiles of solid and liquid lithium

Published in arXiv, 2019

We calculated the momentum distribution n(k) of BCC lithium using all-electron QMC in the grand-canonical ensemble. Kinetic sum rule from finite-size corrected n(k) agrees with thermodynamic limit to 0.1 mha/e. BFD solid - liquid difference agrees well with experiment, but the pseudopotential Compton profile is too narrow due to lack of orthogonalization with core states.

Recommended citation: Y. Yang, N. Hiraoka, K. Matsuda, M. Holzmann, D. M. Ceperley, "Quantum Monte Carlo Compton profiles of solid and liquid lithium, " arXiv: 1912.12295

talks

teaching

PHYS 460 Condensed Matter Physics

Class, University of Illinois Urbana Champaign, Physics Department, 1900

I was the lone TA for this class. I reworked many HW problems and made the solutions. We covered most materials in “The Oxford Solid State Basics” by Steven Simon.

thesis