Quasiparticle band gaps and optical spectra of strained monolayer transition-metal dichalcogenides

Employing the first-principles many-body perturbation theory, we report the excited-state properties, i.e., quasiparticle energy and excitonic effects, of strained monolayer 2H-phase transition-metal dichalcogenides, including ${\mathrm{MoS}}_{2}, {\mathrm{MoSe}}_{2}, {\mathrm{WS}}_{2}$, and ${\mathrm{WSe}}_{2}$. Beyond previous studies that considered uniaxial or biaxial strain, we cover arbitrarily axial strains and find complicated variations of quasiparticle band gaps, band-edge energies, direct-indirect gap transitions, and exciton energies. These results provide a complete picture for straining engineering of electronic structures and optical spectra of two-dimensional transition-metal dichalcogenides. Particularly, combined with high spatial-resolution optical measurements, our calculated results are essential for identifying local strain distribution and understanding the widely observed inhomogeneous free-carrier distributions and photoluminescence in realistic two-dimensional materials.