arXiv subjects

Per S. Schmidt

Publications and source records attributed to Per S. Schmidt.

3 recordsLinked to original sources

arXiv2018

The Computational 2D Materials Database: High-Throughput Modeling and Discovery of Atomically Thin Crystals

We introduce the Computational 2D Materials Database (C2DB), which organises a variety of structural, thermodynamic, elastic, electronic, magnetic, and optical properties of around 1500 two-dimensional materials distributed over more than 30 different crystal structures. Material properties are systematically calculated by state-of-the art density functional theory and many-body perturbation theory (G$_0\!$W$\!_0$ and the Bethe-Salpeter Equation for $\sim$200 materials) following a semi-automated workflow for maximal consistency and transparency. The C2DB is fully open and can be browsed online or downloaded in its entirety. In this paper, we describe the workflow behind the database, present an overview of the properties and materials currently available, and explore trends and correlations in the data. Moreover, we identify a large number of new potentially synthesisable 2D materials with interesting properties targeting applications within spintronics, (opto-)electronics, and plasmonics. The C2DB offers a comprehensive and easily accessible overview of the rapidly expanding family of 2D materials and forms an ideal platform for computational modeling and design of new 2D materials and van der Waals heterostructures.

cond-mat.mes-hall↗

arXiv2017

Simple vertex correction improves GW band energies of bulk and two-dimensional crystals

The GW self-energy method has long been recognized as the gold standard for quasiparticle (QP) calculations of solids in spite of the fact that the neglect of vertex corrections and the use of a DFT starting point lacks rigorous justification. In this work we remedy this situation by including a simple vertex correction that is consistent with an LDA starting point. We analyse the effect of the self-energy by splitting it into a short-range and long-range term which are shown to govern respectively the center and size of the band gap. The vertex mainly improves the short-range correlations and therefore has a small effect on the band gap, while it shifts the band gap center up in energy by around 0.5 eV in good agreement with experiments. Our analysis also explains how the relative importance of short- and long-range interactions in structures of different dimensionality is reflected in their QP energies. Inclusion of the vertex comes at practically no extra computational cost and even improves the basis set convergence compared to GW. The method thus provides an efficient and rigorous improvement over the GW approximation and sets a new standard for quasiparticle calculations of solids.

cond-mat.mtrl-sci↗

arXiv2016

Efficient many-body calculations of 2D materials using exact limits for the screened potential: Band gaps of MoS$_2$, hBN, and phosphorene

Calculating the quasiparticle (QP) band structure of two-dimensional (2D) materials within the GW self-energy approximation has proven to be a rather demanding computational task. The main reason is the strong $\mathbf{q}$-dependence of the 2D dielectric function around $\mathbf{q} = \mathbf{0}$ that calls for a much denser sampling of the Brillouin zone than is necessary for similar 3D solids. Here we use an analytical expression for the small $\mathbf{q}$-limit of the 2D response function to perform the BZ integral over the critical region around $\mathbf{q} = \mathbf{0}$. This drastically reduces the requirements on the $\mathbf{q}$-point mesh and implies a significant computational speed-up. For example, in the case of monolayer MoS$_2$, convergence of the $G_0W_0$ band gap to within $\sim 0.1\,\mathrm{eV}$ is achieved with $12\times 12$ $\mathbf{q}$-points rather than the $36\times 36$ mesh required with discrete BZ sampling techniques. We perform a critical assessment of the band gap of the three prototypical 2D semiconductors MoS$_2$, hBN, and phosphorene including the effect of self-consistency at the GW$_0$ and GW level. The method is implemented in the open source GPAW code.

cond-mat.mtrl-sci↗