Universal Scaling between On-Site Coulomb Repulsion and Numbers of Core and Valence Electrons in Transition Metal Trichalcogenides

Guohua Cao, Chuanqi Xu, Ping Cui, Zhenyu Zhang
May, 2023
Cite DOI

Abstract

Electron correlations that determine a broad spectrum of the physical properties of transition metal compounds are largely manifested by the on-site Coulomb repulsion U, which so far has been mainly evaluated on a case-by-case basis. Here we employ a linear response method based on constrained local density approximation to systematically investigate U in representative classes of transition metal trichalcogenides, with the transition metals covering all the unfilled 3d, 4d, and 5d orbitals. We uncover a characteristic scaling dependence of U on two elemental physical parameters, namely, the numbers of the core and valence electrons. Such a universal scaling law reflects the intuition that more unfilled d electrons residing on a smaller spherical core will feel stronger Coulomb repulsion. Next, by using the artificial intelligence-based SISSO (Sure Independence Screening and Sparsifying Operator) approach, we identify a more sophisticated descriptor that not only further refines the scaling law, but also captures the crystal-field splitting effect as pictorially reflected by invoking an elliptical core instead of a spherical core. The approach developed in this study should find transferability in other classes of transition metal compounds.

Type
2
Publication
Computer Physics Communications
Descriptor Elemental physical parameters Linear response On-site Coulomb repulsion Transition metal trichalcogenides Universal scaling
Chuanqi Xu
Chuanqi Xu
Ph.D. Student

I am a PhD candidate at Yale University. My current research focuses on quantum computing and computer security, where I design novel attacks and defenses targeting quantum computers and quantum cloud providers. Specifically, my work explores security and privacy across the entire technology stack of quantum computers:

  1. Investigating vulnerabilities in quantum processors and qubit technologies.
  2. Developing secure and private quantum computer systems and architecture.
  3. Ensuring the security of quantum algorithms, with a focus on quantum machine learning (QML).

Previously, I worked on RTL design (Verilog) for FPGAs, implementing Post-Quantum Cryptography (PQC) that is secure to both classical and quantum computer attacks.

I am actively seeking roles as a research scientist, software engineer, and quant researcher. I am broadly interested in developing systems and infrastructure, especially for ML/GenAI infrastructure and systems.