CN108509683B

CN108509683B - Simulation design method of two-dimensional layered dirac material

Info

Publication number: CN108509683B
Application number: CN201810169983.XA
Authority: CN
Inventors: 闫翠霞; 宋玲玲; 蔡金明; 叶乾旭; 官雨柔
Original assignee: Kunming University of Science and Technology
Current assignee: Kunming University of Science and Technology
Priority date: 2018-03-01
Filing date: 2018-03-01
Publication date: 2022-05-20
Anticipated expiration: 2038-03-01
Also published as: CN108509683A

Abstract

The invention relates to a simulation design method of a two-dimensional layered dirac material, and belongs to the technical field of dirac material preparation. And (3) based on a single-layer graphene primitive cell, performing single bond connection on a fourth main group atom and a second main group atom in the same plane to form a six-membered ring structure, and preparing the two-dimensional layered dirac simulation material. Theoretical calculation and experiments are combined from a micro scale, a model is built, a theoretical simulation method can be used for deeply researching a complex system in an atomic order, and the structure of the novel two-dimensional layered dirac material is built by taking graphene as a structural prototype. The method adopting theoretical simulation is simple to operate, low in cost, high in accuracy and good in repeatability, and can provide a valuable theoretical research foundation for subsequent experiments.

Description

Simulation design method of two-dimensional layered dirac material

Technical Field

The invention relates to a simulation design method of a two-dimensional layered dirac material, and belongs to the technical field of dirac material preparation.

Background

Dirac cones are a unique band structure with the energy band in a top-to-bottom conical shape at the fermi level separating filled and unfilled electrons. This band structure is called a dirac cone because it satisfies the dirac equation describing the relativistic particle energy-momentum relationship. An electron, described by the dirac cone band, is a particle with a static mass of zero, which behaves like a photon. Research shows that the material with the dirac cone energy band structure has many excellent physical properties, such as very high carrier mobility, abnormal quantum hall effect and the like. To date, hundreds of two-dimensional materials have been discovered, including: simple substance of the fourth main group, binary compound composed of the third and fifth main groups, metal chalcogenide, composite oxide, and the like. But only graphene, silylene (silicane), Germanene (Germanene), partially graphyne (Graphynes), and other minor systems are believed to have the potential for dirac cones.

Due to the uncertainty of the experiment and the limitation of the experimental conditions, it is a complicated and long process to find new dirac materials. However, theoretical calculation can be used for discovering a novel dirac material by designing a new material through simulation and calculating the properties of the new material. Therefore, guidance and theoretical basis are provided for experimental research, and blindness in the experimental process is reduced.

Disclosure of Invention

Aiming at the problems and the defects in the prior art, the invention provides a simulation design method of a two-dimensional layered dirac material. The invention aims at solving the problems that the material with the dirac cone energy band structure is difficult to prepare and the cost is high in experiments, and is realized by the following technical scheme.

A simulation design method of a two-dimensional layered Dirac material comprises the following steps:

based on a single-layer graphene primitive cell, a fourth main group atom and a second main group atom are connected in a single bond in the same plane to form a six-membered ring structure, so that the two-dimensional layered dirac simulation material is prepared, and the specific steps are as follows:

step 1, sequentially expanding single-layer graphene protocells by 2 times and then expanding single-layer graphene protocells by 3 times;

step 2, deleting carbon atoms on a six-ring center by 3 times of the graphene protocell expanded in the step 1, leaving isolated carbon atoms, and expanding the six-ring;

step 3, adding second main group atoms between every two residual carbon atoms in the step 2 to form a single bond;

step 4, replacing the residual carbon atoms in the structure obtained by the treatment in the step 3 with fourth main group atoms;

and 5, optimally designing the structure obtained in the step 4 to obtain the two-dimensional layered dirac simulation material.

The simulation design is built by adopting Materials Studio software to obtain a single-layer graphene primitive cell, and the optimization process in the step 5 is carried out by adopting Vasp software.

The invention has the beneficial effects that: theoretical calculation and experiments are combined from a micro scale, a model is built, a theoretical simulation method can be used for deeply researching a complex system in an atomic order, and the structure of the novel two-dimensional layered dirac material is built by taking graphene as a structural prototype. The method adopting theoretical simulation is simple to operate, low in cost, high in accuracy and good in repeatability, and can provide a valuable theoretical research foundation for subsequent experiments.

Drawings

FIG. 1 is a schematic diagram of a single-layer graphene protocell structure according to the present invention;

FIG. 2 is a schematic structural diagram of a single-layer graphene primitive cell of the present invention after 2 × 2 times expansion of the primitive cell;

FIG. 3 is a schematic structural diagram of the present invention after 2X 2 times of expansion of the primitive cell and 3X 3 times of expansion of the primitive cell;

FIG. 4 is a schematic diagram of the structure of the carbon atoms on the central six-ring that need to be deleted in the present invention;

FIG. 5 is a schematic diagram of the present invention with the carbon atoms on the central six-ring removed;

FIG. 6 is a schematic diagram of the structure of the present invention after adding a second main group atom between two carbon atoms;

FIG. 7 is a schematic diagram showing the structure of the present invention after replacing all carbon atoms in FIG. 6 with atoms of the fourth main group;

FIG. 8 is a schematic diagram of the present invention after adjusting the positions of all the atoms;

FIG. 9 is a schematic structural diagram of an optimized two-dimensional layered hexagonal dirac material primitive cell according to the present invention;

FIG. 10 is a three-dimensional energy band diagram of an optimized two-dimensional layered hexagonal dirac material primitive cell obtained in example 1 of the present invention;

fig. 11 is a phonon spectrum of the optimized two-dimensional layered hexagonal dirac material primitive cell obtained in example 1 of the present invention.

In the figure: 1-carbon atom, 2-unit cell boundary line, 3-carbon atom to be deleted, 4-second main group atom, 5-fourth main group atom.

Detailed Description

The invention is further described with reference to the following drawings and detailed description.

Example 1

The simulation design method of the two-dimensional layered Dirac material comprises the following steps:

step 1, introducing a graphite structure into Materials Studio software, canceling symmetry, deleting a layer of graphite, and moving the remaining layer of graphite to the center; cutting out the obtained single-layer graphene primitive cells (shown in figure 1) on the surface (00-1), and sequentially expanding the single-layer graphene primitive cells by 2 times (shown in figure 2) and further expanding the single-layer graphene primitive cells by 3 times (shown in figure 3);

step 2, deleting 3 × 3 times of carbon atoms on the central six-ring of the graphene protocell expanded in step 1 (the schematic structural diagram of the carbon atoms on the central six-ring needing to be deleted is shown in fig. 4), leaving isolated carbon atoms, and expanding the six-ring (the schematic structural diagram of the carbon atoms on the central six-ring after being deleted is shown in fig. 5);

step 3, adding second main group beryllium atoms between every two residual carbon atoms in the step 2 to form a single bond (the structural schematic diagram of the carbon atoms added with the second main group beryllium atoms between every two carbon atoms is shown in figure 6);

step 4, maintaining a planar structure, replacing the remaining carbon atoms in the structure obtained by processing in step 3 with fourth main group silicon atoms (a schematic structure diagram after replacing all carbon atoms in fig. 6 with the fourth main group atoms is shown in fig. 7), selecting all atoms, adjusting the positions of the atoms in the lattice, and moving the atoms downward by 2 a (a schematic structure diagram after adjusting the positions of all atoms is shown in fig. 8);

and 5, carrying out optimization design on the structure obtained in the step 4 to obtain a two-dimensional layered dirac simulation material, and optimizing by adopting Vasp software, wherein the optimization parameters are set as follows:

the electron-ion interaction is described by adopting an ultra-soft pseudopotential, an exchange-correlation functional is described by adopting local density approximation (LDA-CAPZ), k-point sampling of a Brillouin area is realized by adopting a Monkhorst-pack (MK) scheme, and the structure is optimized; the precision of the main parameters of the structure optimization is set as follows: the plane wave cut-off energy was set to 650eV, and the K-point of the Brillouin zone was selected to be 8X 1.

The optimized two-dimensional layered Dirac simulation material has the structural parameters that:

space group P6/MMM (D6H-1)

Lattice constant: a = b =7.3533 a, c =14.7898 a;

direct coordinates of atoms:

C1:0.3333772482169902 0.6666227817212875 0.5212471974949838

C2: 0.6666517658361568 0.3333482639774277 0.5212126372465681

C3: 0.4999443974391711 0.5000556025283499 0.5211567566391641

C4: 0.4999165494398252 -0.0001100689743162 0.5211367817096422

C5:0.0001100689634875 0.5000834505385250 0.5211367817096422；

the structural parameter data are obtained after structural optimization, and the uniqueness of the two-dimensional layered dirac simulation material can be determined through the position coordinates of six atoms in the primitive cell.

The electronic properties of the two-dimensional layered dirac simulation material are calculated by adopting a first principle, the structural energy band data are calculated as shown in fig. 10, and the phonon spectrum data are calculated as shown in fig. 11, it can be seen from fig. 10 that the energy band of the two-dimensional layered dirac simulation material contains dirac points, which are dirac materials, and it can be seen from fig. 11 that the two-dimensional layered dirac simulation material has a stable structure.

Example 2

step 1, introducing a graphite structure into Materials Studio software, canceling symmetry, deleting a layer of graphite, and moving the remaining layer of graphite to the center; cutting out (00-1) the obtained single-layer graphene primitive cells (as shown in figure 1), and sequentially expanding the single-layer graphene primitive cells by 2 times (as shown in figure 2) and further expanding the single-layer graphene primitive cells by 3 times (as shown in figure 3);

step 2, deleting 3 × 3 times of carbon atoms on the central six-ring of the graphene protocell expanded in step 1 (the structural schematic diagram of the carbon atoms on the central six-ring needing to be deleted is shown in fig. 4 in the selection), leaving isolated carbon atoms, and expanding the six-ring (the structural schematic diagram of the carbon atoms on the central six-ring is shown in fig. 5 in the deletion);

step 3, adding second main group magnesium atoms between every two carbon atoms left in the step 2 to form a single bond (a structural schematic diagram of the carbon atoms added with the second main group atoms between every two carbon atoms is shown in figure 6);

The optimized two-dimensional layered dirac simulation material has the structural parameters:

space group P-3M1(D3D-3)

Lattice constant: a = b =8.7585 a, c =15.55909 a;

direct coordinates of atoms:

C1:0.3333772482169902 0.6666227817212875 0.5212471974949838

C2: 0.3333699423815703 0.6666300875567072 0.5154691494219469

C3: 0.4999175620775867 0.5000824378899342 0.5218100865791058

C4: 0.4998963318596573 -0.0001424724705489 0.5218223503422469

C5: 0.0001424724597203 0.5001036681186922 0.5218223503422469

While the present invention has been described in detail with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, and various changes can be made without departing from the spirit and scope of the present invention.

Claims

1. A simulation design method of a two-dimensional layered Dirac material is characterized by comprising the following steps:

step 1, expanding single-layer graphene protocells by 2 times and then by 3 times;

step 2, deleting carbon atoms on the central six-membered ring by the 3 x 3 times of the graphene protocell expanded in the step 1, and leaving isolated carbon atoms to expand the six-membered ring;

step 3, adding second main group atoms between the rest adjacent carbon atoms in the step 2 to form a single bond;

2. The simulation design method of the two-dimensional layered dirac material according to claim 1, wherein: the simulation design is built by adopting Materials Studio software to obtain a single-layer graphene primitive cell, and Vasp software is adopted to carry out the optimization process in the step 5.