Wavefunction-Free Approach for Predicting Nonlinear Responses in Weyl Semimetals

TL;DR

This paper introduces a wavefunction-free method to predict nonlinear responses in Weyl semimetals, achieving significant computational speedups and enabling efficient material screening for quantum device applications.

Contribution

The authors develop a wavefunction-free formulation for nonlinear responses in Weyl semimetals, drastically improving computational efficiency and broadening the scope of material analysis.

Findings

Achieved 1000-fold speedup in calculations of nonlinear responses.

Discovered Ta$_3$S$_2$ exhibits much larger photocurrents than TaAs.

Derived a wavefunction-free formula for Berry-curvature dipole.

Abstract

By sidestepping the intractable calculations of many-body wavefunctions, density functional theory (DFT) has revolutionized the prediction of ground states of materials. However, predicting nonlinear responses--critical for next-generation quantum devices--still relies heavily on explicit wavefunctions, limiting computational efficiency. In this letter, using the circular photogalvanic effect (CPGE) in Weyl semimetals as a representative example, we realize a 1000-fold computational speedup by eliminating the explicit dependence on wavefunctions. Our approach leverages the one-to-one correspondence between free parameters of Weyl fermions and the associated responses to obtain precise wavefunction-free formulations. Applying our methodology, we systematically investigated known Weyl semimetals and revealed that Ta$_3$S$_2$ exhibits photocurrents an order of magnitude greater than those observed in TaAs, with potential for an additional order-of-magnitude enhancement under strain. To further demonstrate the generality of our approach, we obtained a wavefunction-free formula for the Berry-curvature dipole in Weyl semimetals. Our work paves the way for substantially more efficient screening and optimization of nonlinear electromagnetic properties in topological quantum materials.