Chong Sun

Chong Sun

Understanding the world with numerical simulations.

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A list of all the posts and pages found on the site. For you robots out there is an XML version available for digesting as well.

Pages

Posts

Using VMD to draw molecular orbitals

4 minute read

Published:

A quick tutorial on using VMD to visualize molecular orbitals, or other type of orbitals, defined as a vector (linear combination coefficients of the basis set.)

Notes on generative models

11 minute read

Published:

This post gives a general introduction of popular generative models such as variational autoencoder (VAE), autoregressive models, generative adversarial networks (GANs), and diffusion models.

publications

Determining eigenstates and thermal states on a quantum computer using quantum imaginary time evolution

Published in Nature Physics , 2020

This paper provides a quantum algorithm for imaginary time evolution (ITE). The biggest challenge of implementing ITE on a quantum computer is that the ITE operator is non-unitary. Unlike the popular block encoding approach, our algorithm does not require ancillary qubits. The key is to utilize the entanglement pattern of a physical system.

Recommended citation: Motta, M., Sun, C., Tan, A.T.K. et al. Nat. Phys. 16, 205–210 (2020). https://www.nature.com/articles/s41567-019-0704-4

Finite-temperature density matrix embedding theory

Published in Physical Review B, 2020

This paper provides a new vision on the behavior of entanglement at finite temperature. It also provides a numerical algorithm called finite-temperature density matrix embedding theory (FT-DMET), which is powerful for computing observables and phase diagrams for strongly correlated systems at finite temperature.

Recommended citation: Chong Sun, Ushnish Ray, Zhi-Hao Cui, Miles Stoudenmire, Michel Ferrero, and Garnet Kin-Lic Chan. Phys. Rev. B 101, 075131 (2020) https://journals.aps.org/prb/abstract/10.1103/PhysRevB.101.075131

Ground-state phase diagram of the three-band Hubbard model from density matrix embedding theory

Published in Phys. Rev. Research , 2020

Three-band Hubbard model is a good model-approximation to the two-dimensional cuprate layer, which is the key structure of copper-based high-temperature superconductors. This paper applied density matrix embedding theory (DMET) to simulating the magnetic order and pairing parameters of the three-band Hubbard model with dopping, and shed light on understanding the mechanism of high Tc superconductors.

Recommended citation: Zhi-Hao Cui, Chong Sun, Ushnish Ray, Bo-Xiao Zheng, Qiming Sun, and Garnet Kin-Lic Chan Phys. Rev. Research 2, 043259(2020) https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.2.043259

Waveflow: Enforcing boundary conditions in smooth normalizing flows with application to fermionic wave functions

Published in Pre-print, 2022

This paper applies physical constraints onto normalizing flows in order to sample many-electron wavefunctions. Unlike most wavefunction-based methods where the Slater determinants are used to encode antisymmetry, the antisymmetric property of fermionic wavefunctions is encoded directly in the construction of the normalizing flows with certain boundary conditions. We call the proposed scheme “waveflows”.

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talks

teaching

Teaching experience 1

Undergraduate course, University 1, Department, 2014

This is a description of a teaching experience. You can use markdown like any other post.

Teaching experience 2

Workshop, University 1, Department, 2015

This is a description of a teaching experience. You can use markdown like any other post.