scholarly journals The site-symmetry induced representations of layer groups on the Bilbao Crystallographic Server

2019 ◽  
Vol 52 (5) ◽  
pp. 1214-1221 ◽  
Author(s):  
Gemma de la Flor ◽  
Danel Orobengoa ◽  
Robert A. Evarestov ◽  
Yuri E. Kitaev ◽  
Emre Tasci ◽  
...  
Keyword(s):  
Van Der Waals ◽  
Site Symmetry ◽  
Induced Representations ◽  
Symmetry Approach ◽  
Layered Crystals ◽  
Symmetry Relations ◽  
Layer Groups

The section of the Bilbao Crystallographic Server (http://www.cryst.ehu.es) dedicated to subperiodic groups includes a new tool called LSITESYM for the study of materials with layer and multilayer symmetry. This new program, based on the site-symmetry approach, establishes the symmetry relations between localized and extended crystal states using representations of layer groups. The efficiency and utility of the program LSITESYM is demonstrated by illustrative examples, which include the analysis of phonon symmetry in Aurivillius compounds and in van der Waals layered crystals MoS2 and WS2.

scholarly journals Double crystallographic groups and their representations on the Bilbao Crystallographic Server

2017 ◽  
Vol 50 (5) ◽  
pp. 1457-1477 ◽  
Author(s):  
Luis Elcoro ◽  
Barry Bradlyn ◽  
Zhijun Wang ◽  
Maia G. Vergniory ◽  
Jennifer Cano ◽  
...  
Keyword(s):  
Irreducible Representations ◽  
Site Symmetry ◽  
Crystallographic Groups ◽  
Space Groups ◽  
Symmetry Approach ◽  
Wyckoff Position ◽  
Double Space ◽  
Elementary Band ◽  
Symmetry Relations ◽  
Symmetry Operations

A new section of databases and programs devoted to double crystallographic groups (point and space groups) has been implemented in the Bilbao Crystallographic Server (http://www.cryst.ehu.es). The double crystallographic groups are required in the study of physical systems whose Hamiltonian includes spin-dependent terms. In the symmetry analysis of such systems, instead of the irreducible representations of the space groups, it is necessary to consider the single- and double-valued irreducible representations of the double space groups. The new section includes databases of symmetry operations (DGENPOS) and of irreducible representations of the double (point and space) groups (REPRESENTATIONS DPGandREPRESENTATIONS DSG). The toolDCOMPRELprovides compatibility relations between the irreducible representations of double space groups at differentkvectors of the Brillouin zone when there is a group–subgroup relation between the corresponding little groups. The programDSITESYMimplements the so-called site-symmetry approach, which establishes symmetry relations between localized and extended crystal states, using representations of the double groups. As an application of this approach, the programBANDREPcalculates the band representations and the elementary band representations induced from any Wyckoff position of any of the 230 double space groups, giving information about the properties of these bands. Recently, the results ofBANDREPhave been extensively applied in the description of and the search for topological insulators.

Single oxygen vacancy in BaCoO3: Hybrid DFT calculations and local site symmetry approach

2022 ◽  
Vol 375 ◽  
pp. 115835
Author(s):  
Davis Zavickis ◽  
Guntars Zvejnieks ◽  
Andrei Chesnokov ◽  
Denis Gryaznov
Keyword(s):  
Oxygen Vacancy ◽  
Dft Calculations ◽  
Site Symmetry ◽  
Symmetry Approach ◽  
Local Site ◽  
Single Oxygen

scholarly journals First-principles calculations of oxygen interstitials in corundum: a site symmetry approach

2017 ◽  
Vol 19 (37) ◽  
pp. 25245-25251 ◽  
Author(s):  
Robert A. Evarestov ◽  
Alexander Platonenko ◽  
Denis Gryaznov ◽  
Yuri F. Zhukovskii ◽  
Eugene A. Kotomin
Keyword(s):  
First Principles ◽  
Symmetry Analysis ◽  
Crystalline Lattice ◽  
Site Symmetry ◽  
First Principles Calculations ◽  
Symmetry Approach ◽  
Spatial Configurations ◽  
A Site

Site symmetry analysis allows one to define four possible spatial configurations for inserting O atoms into the α-Al2O3 crystalline lattice.

Site symmetry approach to lattice dynamics of semiconductor superlattices

1991 ◽  
Vol 9 (2) ◽  
pp. 211-217 ◽  
Author(s):  
B.H. Bairamov ◽  
R.A. Evarestov ◽  
Yu.E. Kitaev ◽  
E. Jahne ◽  
M. Delaney ◽  
...  
Keyword(s):  
Lattice Dynamics ◽  
Site Symmetry ◽  
Semiconductor Superlattices ◽  
Symmetry Approach

Van Der Waals Epitaxy of II-Vi Semiconductors on Layered Chalcogenide (0001) Substrates: Towards Buffer Layers for Lattice Mismatched Systems?

1996 ◽  
Vol 441 ◽  
Author(s):  
T. Löher ◽  
A. Klein ◽  
E. Schaar-Gabriel ◽  
R. Rudolph ◽  
Y. Tomm ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Elevated Temperatures ◽  
Lattice Mismatch ◽  
Van Der Waals ◽  
Growth Front ◽  
Buffer Layers ◽  
Morphological Properties ◽  
Layered Semiconductor ◽  
Layered Crystals ◽  
Small Lattice

AbstractThe II-VI semiconductor CdS was grown by molecular beam epitaxy on the van der Waals faces of the layered semiconductor InSe. Chemical, electronic and morphological properties of the deposited films were investigated by means of low energy electron diffraction (LEED), soft x-ray photoelectron spectroscopy (SXPS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). In contrast to observations made on other layered crystals, nucleation of CdS on InSe is possible also at elevated temperatures which is attributed to the small lattice mismatch. The growth front of CdS corresponds to the sulfur terminated polar (111)-B surface which has a strong tendency to form facets.

scholarly journals Redetermination of 1,3,6,8-tetraazatricyclo[4.4.1.13,8]dodecane

2014 ◽  
Vol 70 (3) ◽  
pp. o266-o266 ◽  
Author(s):  
Augusto Rivera ◽  
Jaime Ríos-Motta ◽  
Michael Bolte
Keyword(s):  
Crystal Structure ◽  
Title Compound ◽  
Room Temperature ◽  
Van Der Waals ◽  
The Other ◽  
Site Symmetry ◽  
Asymmetric Unit ◽  
Temperature Study ◽  
Compound C ◽  
Van Der Waals Contacts

The structure of the title compound, C8H16N4, which consists of four fused seven-membered rings, has been redetermined at 173 K. This redetermination corrects the orientation of two H atoms, which were located at unrealistic positions in the original room-temperature study [Murray-Rust (1974).J. Chem. Soc. Perkin Trans. 2, pp. 1136–1141]. The complete molecule is generated by -42msymmetry, with one quarter of a molecule [one N atom (site symmetrym), two C atoms (one with site symmetrymand the other with site symmetry 2) and two H atoms] in the asymmetric unit. No directional interactions beyond van der Waals contacts are apparent in the crystal structure.

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