A Pathway to Efficient Simulations of Charge Density Waves in Transition Metal Dichalcogenides: A Case Study for TiSe2

Abstract

Charge density waves (CDWs) in transition metal dichalcogenides are the subject of growing scientific interest due to their rich interplay with exotic phases of matter and their potential technological applications. Here, using density functional theory with advanced meta-generalized gradient approximations (meta-GGAs) and linear response time-dependent density functional theory (TDDFT) with state-of-the-art exchange-correlation kernels, we investigate the electronic, vibrational, and optical properties in 1T-TiSe2 with and without CDW. In both bulk and monolayer TiSe2, the electronic bands and phonon dispersions in either normal (semi-metallic) or CDW (semiconducting) phase are described well via meta-GGAs, which separate the valence and conduction bands just as HSE06 does but with significantly more computational feasibility. Instead of the underestimated gap with standard exchange-correlation approximations and the overestimated gap with screened hybrid functional HSE06, the band gap of the monolayer TiSe2 CDW phase calculated by the meta-GGA MVS (151 meV) is consistent with the angle-resolved photoemission spectroscopy (ARPES) gap of 153 meV measured at 10 K. In addition, the gap of bulk TiSe2 CDW phase reaches 67 meV within the TASK approximation, close to the ARPES gap of 82 meV. Regarding excitations of many-body nature, for bulk TiSe2 in normal and CDW phases, the experimentally observed humps of electron energy loss spectroscopy and plasmon peak are successfully reproduced in TDDFT, without an obvious kernel dependence. To unleash the full scientific and technological potential of CDWs in transition metal dichalcogenides, the chemical doping, heterostructure engineering, and pump-probe techniques are needed. Our study opens the door to simulating these complexities in CDW compounds from first principles by revealing meta-GGAs as an accurate low-cost alternative to HSE06.

22 pages, 4 figures, Supplementary Materials

References in corpus (11)

• Many-body perturbation theory calculations using the yambo code
• Unfolding first-principles band structures
• Semimetal to semimetal charge density wave transition in 1T-TiSe${}_2$
• Doping nature of native defects in 1T-TiSe2
• Testing Electron-phonon Coupling for the Superconductivity in Kagome Metal $\mathrm{Cs}{\mathrm{V}}_3\mathrm{S}{\mathrm{b}}_5$
• Reliable lattice dynamics from an efficient density functional
• Opening band gaps of low-dimensional materials at the meta-GGA level of density functional approximations
• Constraint-based Wavevector- and Frequency-dependent Exchange-Correlation Kernel of the Uniform Electron Gas
• Dramatic Plasmon Response to the Charge-Density-Wave Gap Development in $1\text{T}-{\mathrm{TiSe}}_2$
• Understanding plasmon dispersion in nearly-free-electron metals: the relevance of exact constraints for novel exchange-correlation kernels within time-dependent density functional theory
• Primitive to conventional geometry projection for efficient phonon transport calculations

Cited by in corpus (4)

• Exchange-Correlation Functionals in 2D Materials: Applications, Challenges, and Limitations
• Excitons and Optical Response in Excitonic Insulator Candidate TiSe${}_2$
• Revisiting the charge-density-wave superlattice of 1$T$-TiSe${}_2$
• Engineering correlated Dirac fermions and flat bands on SiC with transition-metal adatom lattices