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.Comment: Add journal reference and DOI; Minor updates to figures and wordin

Deilmann, Thorsten

Gath, Jakob

Gjerding, Morten N.

Haastrup, Sten

Hinsche, Nicki F.

Jacobsen, Karsten W.

Larsen, Peter M.

Mortensen, Jens Jørgen

Olsen, Thomas

Pandey, Mohnish

Riis-Jensen, Anders C.

Schmidt, Per S.

Strange, Mikkel

Thygesen, Kristian S.

Torelli, Daniele

English

arXiv

In his comment Mazdziarz 2019 (2D Mater. 6 048001) raises doubts concerning the reliability of our test for dynamical (in particular elastic) stability of monolayer materials, which neglects the shear components of the stiffness tensor and only considers the sign of the planar stiffness coefficients. We agree that our analysis has not been complete, but find that it suffices in practice except for very few cases (less than 1% of the materials). Nevertheless, for completeness we are currently calculating the shear components of the elastic tensor for all the materials in the C2DB

Schmidt, Per Simmendefeldt

Hinsche, Nicki Frank

Gjerding, Morten Niklas

Larsen, Peter Mahler

Riis-Jensen, Anders Christian

Jacobsen, Karsten Wedel

Thygesen, Kristian Sommer

Online Research Database In Technology

  General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.   Users may download and print one copy of any publication from the public portal for the purpose of private study or research.  You may not further distribute the material or use it for any profit-making activity or commercial gain  You may freely distribute the URL identifying the publication in the public portal  If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.         Downloaded from orbit.dtu.dk on: Sep 11, 2019Reply to comment on 'The Computational 2D Materials Database: high-throughputmodeling and discovery of atomically thin crystals'Haastrup, Sten; Strange, Mikkel; Pandey, Mohnish; Deilmann, Thorsten; Schmidt, Per Simmendefeldt;Hinsche, Nicki Frank; Gjerding, Morten Niklas; Torelli, Daniele; Larsen, Peter Mahler; Riis-Jensen,Anders ChristianPublished in:2D materialsLink to article, DOI:10.1088/2053-1583/ab2f00Publication date:2019Document VersionPublisher's PDF, also known as Version of recordLink back to DTU OrbitCitation (APA):Haastrup, S., Strange, M., Pandey, M., Deilmann, T., Schmidt, P. S., Hinsche, N. F., ... Thygesen, K. S. (2019).Reply to comment on 'The Computational 2D Materials Database: high-throughput modeling and discovery ofatomically thin crystals'. 2D materials, 6(4), [048002]. https://doi.org/10.1088/2053-1583/ab2f002D MaterialsCOMMENTS AND REPLIES • OPEN ACCESSReply to comment on ‘The Computational 2DMaterials Database: high-throughput modeling anddiscovery of atomically thin crystals’To cite this article: Sten Haastrup et al 2019 2D Mater. 6 048002 View the article online for updates and enhancements.Recent citationsProposal for Reconfigurable MagneticTunnel Diode and TransistorErsoy aolu et al-This content was downloaded from IP address 192.38.67.116 on 15/08/2019 at 11:25© 2019 IOP Publishing LtdIn our original paper [2], we described our strat­egy for testing whether a given hypothetized 2D mat­erial would be dynamically stable, i.e. whether it would spontaneously distort if all constraints imposed on the calculation (symmetries and unit cell size) were relaxed. In other words, the test for dynamical stability should assess whether the configuration of the given material represents a minimum or a saddle point of the potential energy surface. Regarding the atomic posi­tions within the unit cell, we calculate the phonons at the corners of the Brillouin zone boundary (specifi­cally the Γ­point phonons of the 2 × 2 repeated cell).The material is classified as dynamically unstable if at least one phonon with imaginary frequency is found. Concerning the shape of the unit cell, we calculate the components of the stiffness tensor corresponding to uniaxial deformations along the x, and y ­axis, namely the C11, C22, and C12 components in the Voigt notation. A material is classified as dynamically unstable if either C11 or C22 is negative.As pointed out in the comment, the correct test for dynamical stability would involve, in addition to the phonon analysis, a diagonalization of the full stiffness tensor to check for negative eigenvalues. By considering only the sign of C11 or C22 there is a risk that a material is incorrectly classified as dynamically stable when in reality it would undergo a shear deformation.We have calculated the full 3× 3 stiffness tensor,C, for 378 materials in the C2DB. We picked this set of materials because we already had calculated the shear deformations in connection with the calculation of their piezoelectric tensors. They cover representatives from all five types of 2D Bravais lattices. In figure 1 we show the minimum eigenvalue of C plotted against min{C11,C22}. There are 36 materials in the greyshaded area where our original assessment of dynami­cal stability based on the C11 and C22 comp onents is wrong. Most of these are materials in the GeS2 struc­ture prototype. However, 34 of these have at least one imaginary zone boundary phonon and would there­fore be classified as dynamically unstable in any case. Therefore, the stronger criterion based on the full stiff­ness tensor only leads to a different conclusion for two materials, namely GeSe2 in the GeS2 prototype and I2Sb2 in the CuI prototype, which are now classified as dynamically unstable.Maździarz highlights three specific materials fromC2DB , namely Au2O2–GaS, Ta2Se2–GaS, and Re2O2–FeSe, and criticises that (1) despite the hexagonal and cubic symmetries of the lattices C11 and C22 are not equal for these materials, and (2) the elastic stabil­ity of the crystals is not reflected by the signs of C11 and C22. Regarding (1), we acknowledge that C11 and C22 should be equal in these cases, but according to our calcul ations they deviate by 1.1%, 0.8%, and 9%, respectively. The average deviation for the 531 mat­erials in C2DB with hexagonal or cubic symmetry is 1.2%, see figure 2. This is obviously due to numerics S Haastrup et alReply to comment on: ‘The computational 2D materials database: high-throughput modeling and discovery of atomically thin crystals’0480022D MATER.© 2019 IOP Publishing Ltd62D Mater.2DM2053-158310.1088/2053-1583/ab2f004132D MaterialsIOP24July2019Reply to comment on ‘The Computational 2D Materials Database: high-throughput modeling and discovery of atomically thin crystals’Sten Haastrup1 , Mikkel Strange1, Mohnish Pandey1, Thorsten Deilmann1 , Per S Schmidt1, Nicki F Hinsche1 , Morten N Gjerding1 , Daniele Torelli1 , Peter M Larsen1, Anders C Riis-Jensen1, Jakob Gath1, Karsten W Jacobsen1, Jens Jørgen Mortensen1, Thomas Olsen1  and Kristian S Thygesen1,21 CAMD, Department of Physics, Technical University of Denmark2 Center for Nanostructured Graphene (CNG), Technical University of DenmarkE-mail: thygesen@fysik.dtu.dkKeywords: 2D materials, high­throughput, database, density functional theoryAbstractIn his comment Maździarz 2019 (2D Mater. 6 048001) raises doubts concerning the reliability of our test for dynamical (in particular elastic) stability of monolayer materials, which neglects the shear components of the stiffness tensor and only considers the sign of the planar stiffness coefficients. We agree that our analysis has not been complete, but find that it suffices in practice except for very few cases (less than 1% of the materials). Nevertheless, for completeness we are currently calculating the shear components of the elastic tensor for all the materials in the C2DB.COMMENTS AND REPLIES2019Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence.Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.RECEIVED 16 April 2019REVISED  12 June 2019ACCEPTED FOR PUBLICATION  3 July 2019PUBLISHED   24 July 2019OPEN ACCESShttps://doi.org/10.1088/2053­1583/ab2f002D Mater. 6 (2019) 0480022S Haastrup et alas we also write in our original paper (page 9): ‘for the isotropic materials MoS2, WSe2 and WS2, C11 and C22 should be identical, and we see a variation of up to 0.6%. This provides a test of how well converged the values are with respect to numer ical settings.’ The deviation of 9% for Re2O2–FeSe is an outlier and we speculate that it arises due to the strong dynamical instability of this material (see below). We note that we could have decided to symmetrise the elastic ten­sors by hand such as to exactly reflect the symmetry of the lattice. We have, however, refrained from such sym­metrisation procedure because we believe it is relevant and more transparent to provide the raw rather than post­processed data. Similar considerations apply to many other quantities in C2DB. Regarding (2) we can essentially refer to the discussion in the first part of this paper. After calculating the full stiffness tensor for the three materials we obtain the same conclusions regard­ing the elastic stability of these materials as suggested in the Comment. However, as was the case for 99.5% Figure 1. The minimum eigenvalue of the full 3× 3 stiffness tensor plotted against the smallest of the two uniaxial stiffness coefficients. Conclusions regarding the elastic stability is changed for the 36 materials in the grey shaded region. However, all of these except for the two materials indicated by red circles are dynamically unstable due to imaginary zone boundary phonons.Figure 2. The two in­plane elastic constants, C11 and C22, plotted against each other for 531 materials in C2DB with either hexagonal or cubic crystal symmetry. Ideally, the two should be equal but due to numerical uncertainties in practice they are not. The three materials discussed in the text are highlighted. The mean relative deviation between the two components for all the materials is 1.2%.2D Mater. 6 (2019) 0480023S Haastrup et alof the 378 test mat erials discussed above, irrespective of the stiffness tensor all three materials are correctly categorised as dynamically unstable in C2DB because they have zone boundary phonons with imaginary fre­quencies.Despite the fact that only 0.5% out of the set of 378 materials are affected, we have decided to calculate the full stiffness tensor for all of the approximately 4000 materials currently in the C2DB. The full stiffness ten­sors for the 378 materials have already been made avail­able in the C2DB, and data for the remaining materials will be available as soon as the calculations are done.AcknowledgmentsThe Center for Nanostructured Graphene is sponsored by the Danish National Research Foundation, Project DNRF103. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant agreement No. 773122, LIMA).ORCID iDsSten Haastrup  https://orcid.org/0000­0003­3696­0356Thorsten Deilmann  https://orcid.org/0000­0003­4165­2446Nicki F Hinsche  https://orcid.org/0000­0002­0176­6038Morten N Gjerding  https://orcid.org/0000­0002­5256­660XDaniele Torelli  https://orcid.org/0000­0002­4861­0268Thomas Olsen  https://orcid.org/0000­0001­6256­9284Kristian S Thygesen  https://orcid.org/0000­0001­5197­214XReferences	[1]	 Maździarz M 2019 2D Mater. 6 048001	[2]	 Haastrup S et al 2018 2D Mater. 5 042002 2D Mater. 6 (2019) 048002

Reply to comment on '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 ( and the Bethe–Salpeter equation for  ∼250 materials) following a semi-automated workflow for maximal consistency and transparency. The C2DB is fully open and can be browsed online (http://c2db.fysik.dtu.dk) 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

Larsen, Peter M

The Computational 2D Materials Database: high-throughput modeling and discovery of atomically thin crystals

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

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

Abstract

Similar works

Full text

Available Versions

Online Research Database In Technology

Online Research Database In Technology