How dielectric screening in two-dimensional crystals affects the convergence of excited-state calculations: Monolayer MoS2

By F. Huser, T. Olsen, Kristian Sommer Thygesen. 2013

212 citations recorded by the source corpus.

We present first-principles many-body calculations of the dielectric constant, quasiparticle band structure, and optical absorption spectrum of monolayer MoS$_2$ using a supercell approach. As the separation between the periodically repeated layers is increased, the dielectric function of the layer develops a strong $q$ dependence around $q=0$. This implies that denser $k$-point grids are required to converge the band gap and exciton binding energies when large supercells are used. In the limit of infinite layer separation, here obtained using a truncated Coulomb interaction, a $45\times45$ $k$-point grid is needed to converge the G$_0$W$_0$ band gap and exciton energy to within 0.1 eV. We provide an extensive comparison with previous studies and explain agreement and variations in the results. It is demonstrated that too coarse $k$-point sampling and the interactions between the repeated layers have opposite effects on the band gap and exciton energy, leading to a fortuitous error cancellation in the previously published results.

Subfields: Electrical and Electronic Engineering, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/2c4025bf3829e321d30239322bc4fcc2dc970cf5

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Citations in the corpus

VASPKIT: A user-friendly interface facilitating high-throughput computing and analysis using VASP code (2019, background): “(37)-(41) are not well-defined for low-dimensional materials since the dielectric function is not straightforward and depends on the thickness of the vacuum layer when the low-dimensional systems are simulated using a periodic stack of layers with sufficiently large interlayer distance L to avoid ar”
Excitons in van der Waals heterostructures: The important role of dielectric screening (2015, methodology): “As reported previously [5,16], BSE binding energies in 2D materials are extremely sensitive to the k-point grid.”
Isolation and characterization of few-layer black phosphorus (2014, background): “85 eV, which lies in the range of values reported in the literature [33] and give us confidence in the choice of the B3LYP functional for the calculation of the electronic structure of the monolayer and, possibly, of few-layer systems.”
The Computational 2D Materials Database: high-throughput modeling and discovery of atomically thin crystals (2018, background): “In contrast to the dielectric function, whose definition for a 2D material is not straightforward [119], the polarisability allows for a natural generalisation to 2D by considering the induced dipole moment per unit area, Γ M K Γ Band structure −7 −6 −5 −4 −3”
2D semiconducting materials for electronic and optoelectronic applications: potential and challenge (2020, background): “The effect of dielectric screening was also studied: High-k dielectric materials were reported to enhance the mobility due to screening effects [88, 90, 109] attributed to the top-gate capacitance [110].”