Band gap renormalization in diamond using one-shot method: Difference between revisions

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   {{TAGBL|PHON_TLIST}} = 0.0
   {{TAGBL|PHON_TLIST}} = 0.0


*The tags with "PHON_" control the electron phonon options. {{TAG|PHON_LMC}} enables electron phonon calculations using Monte Carlo sampling. By selecting {{TAG|PHON_NSTRUCT}}=0 a one-shot configuration is obtained. The {{TAG|PHON_NTLIST}} selects the number of temperatures for which the structure with the one shot calculation is obtained. This requires also the list of temperatures {{TAG|PHON_TLIST}} which have exact that number of elements.
*The tags with "PHON_" control the electron-phonon couplings (EPC). {{TAG|PHON_LMC}} enables electron-phonon coupling in the calculations using Monte Carlo sampling. By selecting {{TAG|PHON_NSTRUCT}}=0 a one-shot configuration (ZG configuration) is obtained. The tag {{TAG|PHON_NTLIST}} selects the number of temperatures for which the structure with the one shot calculation is obtained. This requires also the list of temperatures given by {{TAG|PHON_TLIST}} which have exact {{TAG|PHON_NTLIST}} number of elements.
*{{TAG|IBRION}}=6 is selected to obtain the eigenvectors and eigenvalues of the dynamical matrix at the Gamma point.
*{{TAG|IBRION}}=6 is selected to obtain the eigenvectors and eigenvalues of the dynamical matrix at the Gamma point.


== Calculation ==
== Calculation ==


This example will use a [[:Electron-phonon interactions theory#ZG configuration (one-shot method)|one-shot method]], where only a single structure comprising the electron-phonon interactions is required for a given temperature.
This example will use a [[:Electron-phonon interactions theory#ZG configuration (one-shot method)|one-shot method]], where only a single structure comprising the EPC is required for a given temperature.


The calculation consists of the following steps:
The calculation consists of two steps:
#Obtain new "distorted" {{TAG|POSCAR}} file which contains the electron-phonon interactions. At zero temperature that file is called '''POSCAR.T=0.'''.
#Obtain new "distorted" {{TAG|POSCAR}} file which contains the EPC. This calculation also contains the band gap of the original structure.  
#Execute simple DFT calculation for the new structure to obtain the band gap.
#Execute simple DFT calculation for the EPC structure to obtain the band gap.
#Optional: execute DFT calculation for the original {{TAG|POSCAR}} file to obtain the band gap of the structure without electron-phonon interactions using the same calculational parameters as in the previous step. Since the phonon calculation from the first step contains the band structure, this step can be skipped if the calculational parameters are the same in that step as for the second step.
#Extract ZPR as the difference between the band gaps from the two calculations.
 
 
=== Step 1 obtain structure containing EPC ===
 
To run the calculation '''POSCAR.init''' needs to be copied to '''POSCAR''' and '''INCAR.init''' to '''INCAR'''.
 
Execute VASP.
 
Copy the {{TAG|OUTCAR}} file to '''OUTCAR.init'''. It will be later used for the band gap of the "undistorted" structure.
 
The new {{TAG|POSCAR}} file containing the configurations according to the electron-phonon couplings is given as '''POSCAR.T=0.'''.  
 
=== Step 2 calculate electronic levels of structure containing EPC ===
 
Copy the file '''POSCAR.T=0.''' to '''POSCAR'''.
 
Delete all the lines in the {{TAG|INCAR}} file related to EPC so that it looks like the following:
System = cd-C
PREC = Accurate
ALGO = FAST
ISMEAR = 0; SIGMA = 0.1;
 
Execute VASP.
 
Copy '''OUTCAR''' to '''OUTCAR.T=0.".
 
=== Step 3 extract ZPR ===


=== Step 1 obtained cell containing electron-phonon interactions ===


== Download ==  
== Download ==  

Revision as of 12:30, 19 August 2020

Task

Calculating the zero-point renormalization of the band gap in cubic diamond carbon.

Input

POSCAR

C_128_fcc
   1.00000000000000
    0.00000000   7.13397200   7.13397200
    7.13397200   0.00000000   7.13397200
    7.13397200   7.13397200   0.00000000
   C
  128
Direct
   0.00000000   0.00000000   0.00000000
   0.25000000   0.00000000   0.00000000
   0.50000000   0.00000000   0.00000000
   0.75000000   0.00000000   0.00000000
   0.00000000   0.25000000   0.00000000
   0.25000000   0.25000000   0.00000000
   0.50000000   0.25000000   0.00000000
   0.75000000   0.25000000   0.00000000
   0.00000000   0.50000000   0.00000000
   0.25000000   0.50000000   0.00000000
   0.50000000   0.50000000   0.00000000
   0.75000000   0.50000000   0.00000000
   0.00000000   0.75000000   0.00000000
   0.25000000   0.75000000   0.00000000
   0.50000000   0.75000000   0.00000000
   0.75000000   0.75000000   0.00000000
   0.00000000   0.00000000   0.25000000
   0.25000000   0.00000000   0.25000000
   0.50000000   0.00000000   0.25000000
   0.75000000   0.00000000   0.25000000
   0.00000000   0.25000000   0.25000000
   0.25000000   0.25000000   0.25000000
   0.50000000   0.25000000   0.25000000
   0.75000000   0.25000000   0.25000000
   0.00000000   0.50000000   0.25000000
   0.25000000   0.50000000   0.25000000
   0.50000000   0.50000000   0.25000000
   0.75000000   0.50000000   0.25000000
   0.00000000   0.75000000   0.25000000
   0.25000000   0.75000000   0.25000000
   0.50000000   0.75000000   0.25000000
   0.75000000   0.75000000   0.25000000
   0.00000000   0.00000000   0.50000000
   0.25000000   0.00000000   0.50000000
   0.50000000   0.00000000   0.50000000
   0.75000000   0.00000000   0.50000000
   0.00000000   0.25000000   0.50000000
   0.25000000   0.25000000   0.50000000
   0.50000000   0.25000000   0.50000000
   0.75000000   0.25000000   0.50000000
   0.00000000   0.50000000   0.50000000
   0.25000000   0.50000000   0.50000000
   0.50000000   0.50000000   0.50000000
   0.75000000   0.50000000   0.50000000
   0.00000000   0.75000000   0.50000000
   0.25000000   0.75000000   0.50000000
   0.50000000   0.75000000   0.50000000
   0.75000000   0.75000000   0.50000000
   0.00000000   0.00000000   0.75000000
   0.25000000   0.00000000   0.75000000
   0.50000000   0.00000000   0.75000000
   0.75000000   0.00000000   0.75000000
   0.00000000   0.25000000   0.75000000
   0.25000000   0.25000000   0.75000000
   0.50000000   0.25000000   0.75000000
   0.75000000   0.25000000   0.75000000
   0.00000000   0.50000000   0.75000000
   0.25000000   0.50000000   0.75000000
   0.50000000   0.50000000   0.75000000
   0.75000000   0.50000000   0.75000000
   0.00000000   0.75000000   0.75000000
   0.25000000   0.75000000   0.75000000
   0.50000000   0.75000000   0.75000000
   0.75000000   0.75000000   0.75000000
   0.18750000   0.18750000   0.18750000
   0.43750000   0.18750000   0.18750000
   0.68750000   0.18750000   0.18750000
   0.93750000   0.18750000   0.18750000
   0.18750000   0.43750000   0.18750000
   0.43750000   0.43750000   0.18750000
   0.68750000   0.43750000   0.18750000
   0.93750000   0.43750000   0.18750000
   0.18750000   0.68750000   0.18750000
   0.43750000   0.68750000   0.18750000
   0.68750000   0.68750000   0.18750000
   0.93750000   0.68750000   0.18750000
   0.18750000   0.93750000   0.18750000
   0.43750000   0.93750000   0.18750000
   0.68750000   0.93750000   0.18750000
   0.93750000   0.93750000   0.18750000
   0.18750000   0.18750000   0.43750000
   0.43750000   0.18750000   0.43750000
   0.68750000   0.18750000   0.43750000
   0.93750000   0.18750000   0.43750000
   0.18750000   0.43750000   0.43750000
   0.43750000   0.43750000   0.43750000
   0.68750000   0.43750000   0.43750000
   0.93750000   0.43750000   0.43750000
   0.18750000   0.68750000   0.43750000
   0.43750000   0.68750000   0.43750000
   0.68750000   0.68750000   0.43750000
   0.93750000   0.68750000   0.43750000
   0.18750000   0.93750000   0.43750000
   0.43750000   0.93750000   0.43750000
   0.68750000   0.93750000   0.43750000
   0.93750000   0.93750000   0.43750000
   0.18750000   0.18750000   0.68750000
   0.43750000   0.18750000   0.68750000
   0.68750000   0.18750000   0.68750000
   0.93750000   0.18750000   0.68750000
   0.18750000   0.43750000   0.68750000
   0.43750000   0.43750000   0.68750000
   0.68750000   0.43750000   0.68750000
   0.93750000   0.43750000   0.68750000
   0.18750000   0.68750000   0.68750000
   0.43750000   0.68750000   0.68750000
   0.68750000   0.68750000   0.68750000
   0.93750000   0.68750000   0.68750000
   0.18750000   0.93750000   0.68750000
   0.43750000   0.93750000   0.68750000
   0.68750000   0.93750000   0.68750000
   0.93750000   0.93750000   0.68750000
   0.18750000   0.18750000   0.93750000
   0.43750000   0.18750000   0.93750000
   0.68750000   0.18750000   0.93750000
   0.93750000   0.18750000   0.93750000
   0.18750000   0.43750000   0.93750000
   0.43750000   0.43750000   0.93750000
   0.68750000   0.43750000   0.93750000
   0.93750000   0.43750000   0.93750000
   0.18750000   0.68750000   0.93750000
   0.43750000   0.68750000   0.93750000
   0.68750000   0.68750000   0.93750000
   0.93750000   0.68750000   0.93750000
   0.18750000   0.93750000   0.93750000
   0.43750000   0.93750000   0.93750000
   0.68750000   0.93750000   0.93750000
   0.93750000   0.93750000   0.93750000

KPOINTS

K-Points
 0
Gamma
 1  1  1
 0  0  0

INCAR

general:
 System = cd-C
 PREC = Accurate
 ALGO = FAST
 ISMEAR = 0 
 SIGMA = 0.1;
 IBRION = 6
 PHON_LMC = .TRUE.
 PHON_NSTRUCT = 0
 PHON_NTLIST = 1
 PHON_TLIST = 0.0
  • The tags with "PHON_" control the electron-phonon couplings (EPC). PHON_LMC enables electron-phonon coupling in the calculations using Monte Carlo sampling. By selecting PHON_NSTRUCT=0 a one-shot configuration (ZG configuration) is obtained. The tag PHON_NTLIST selects the number of temperatures for which the structure with the one shot calculation is obtained. This requires also the list of temperatures given by PHON_TLIST which have exact PHON_NTLIST number of elements.
  • IBRION=6 is selected to obtain the eigenvectors and eigenvalues of the dynamical matrix at the Gamma point.

Calculation

This example will use a one-shot method, where only a single structure comprising the EPC is required for a given temperature.

The calculation consists of two steps:

  1. Obtain new "distorted" POSCAR file which contains the EPC. This calculation also contains the band gap of the original structure.
  2. Execute simple DFT calculation for the EPC structure to obtain the band gap.
  3. Extract ZPR as the difference between the band gaps from the two calculations.


Step 1 obtain structure containing EPC

To run the calculation POSCAR.init needs to be copied to POSCAR and INCAR.init to INCAR.

Execute VASP.

Copy the OUTCAR file to OUTCAR.init. It will be later used for the band gap of the "undistorted" structure.

The new POSCAR file containing the configurations according to the electron-phonon couplings is given as POSCAR.T=0..

Step 2 calculate electronic levels of structure containing EPC

Copy the file POSCAR.T=0. to POSCAR.

Delete all the lines in the INCAR file related to EPC so that it looks like the following: 

System = cd-C
PREC = Accurate
ALGO = FAST
ISMEAR = 0; SIGMA = 0.1;

Execute VASP.

Copy OUTCAR to OUTCAR.T=0.".

Step 3 extract ZPR

Download

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