Density Functional Theory Examples

Description

A set of four quantum espresso simulation configurations to solve for various material/chemical properties.

Installation

Install the latest Python and Quantum Espresso (QE) versions, and ensure the QE binaries pw.x and bands.x are your $PATH variable.

Usage

diamond-scf Usage

Run the e-cutoff.py,k-points.py, and lattice.py scripts in the diamond-scf directory, and modify the QE input file diamond-scf.in as necessary to maintain convergence

diamond-bands Usage

Run the diamond-bands.py script in the diamond-bands directory to automatically calculate the self-consistent field electron density, and to calculate the band structure across the various k-points defined in diamond-bands-make.in.

graphene-bands Usage

Run the graphene-bands.py script in the graphene-bands directory to automatically calculate the self-consistent field electron density, and to calculate the band structure across the various k-points defined in graphene-bands-make.in.

methane Usage

Simply run the command rw.x < methane.in > methane.out to have Quantum Espresso optimize the methane structure! To change the initial guess, generate new hydrogren positions via initial-positions.py and copy/paste them into the ATOMIC_POSITIONS in the methane.in file. To visualize the data, load the output file into XCrysgen

Table of Contents

• test.py - Little script which runs all simulations included in this repository

diamond-scf Contents

Input Files - Diamond Self-Consistent Field

• e-cutoff.py - Python script which tests various energy cutoff values, and plots/tests for convergence for diamond
• k-points.py - Python script which tests various k-lattice configurations, and plots/tests for convergence for diamond
• lattice.py - Python script which tests various lattice constants for diamond, and calculates its bulk modulus
• diamond-scf.in - Quantum Espresso (QE) input file modified by above python scripts for testing
• C.UPF - Atomic orbital data for carbon to use as initial SCF guess

Output Files/Directories - Diamond Self-Consistent Field

• e-cutoff.out - csv-like file for energy cutoff and lattice energy in Rydberg
• k-outputs.out - csv-like file for k-points and lattice energy in Rydberg
• lattice_outputs.out - csv-like file for lattice constant and lattice energy in Rydberg
• e_cutoff-run_files - All QE files related to energy cutoff
• k_points-run_files - All QE files related to k-points
• lattice-run_files - All QE files related to lattice
• tmp - Temporary directory which stores the solved e-density

diamond-bands Contents

Input Files - Diamond Bands

• diamond-bands.py - Python script which runs the scf to generate e-density, then tests various points in K space, and plots the bands
• diamond-scf.in - QE input file with diamond lattice parameters, which is run by diamond-bands.py to generate e-density in tmp
• diamond-bands-make.in - QE input file which defines which points to calculate bands in k-space
• diamond-gnu.in - QE file which processes the bands from diamond-bands-make.in to generate bandsdata.gnu
• C.UPF - Atomic orbital data for carbon to use as initial SCF guess

Output Files/Directories - Diamond Bands

• bandsdata.gnu - GNU file which contains all the band data generated from diamond-bands-make.in and is parsed by diamond-bands.py to graph the band structure
• diamond-band-make.out - QE output file from diamond-bands-make.in
• diamond-gnu.out - QE output file from diamond-gnu.in
• diamond-scf.out QE output file from the SCF method
• tmp - Temporary directory which stores the solved e-density
• bandsdata - Contains band data but not parsed by diamond-bands.py
• input_tmp.in - Autogenerated, not used
• bandsdata.rap - Autogenerated, not used

graphene-bands Contents

Input Files - Graphene

• graphene-bands.py - Python script which runs the scf to generate e-density, then tests various points in K space, and plots the bands
• graphene-scf.in - QE input file with graphene lattice parameters, which is run by graphene-bands.py to generate e-density in tmp. The primitive cell (PC) is set to be large enough in Z such that the graphene is modeled as a sheet
• graphene-bands-make.in - QE input file which defines which points to calculate bands in k-space
• graphene-gnu.in - QE file which processes the bands from graphene-bands-make.in to generate bandsdata.gnu
• C.UPF - Atomic orbital data for carbon to use as initial SCF guess

Output Files/Directories - Graphene

• bandsdata.gnu - GNU file which contains all the band data generated from graphene-bands-make.in and is parsed by graphene-bands.py to graph the band structure
• graphene-band-make.out - QE output file from graphene-bands-make.in
• graphene-gnu.out - QE output file from graphene-gnu.in
• graphene-scf.out QE output file from the SCF method
• tmp - Temporary directory which stores the solved e-density
• bandsdata - Contains band data but not parsed by graphene-bands.py
• input_tmp.in - Autogenerated, not used
• bandsdata.rap - Autogenerated, not used

methane Contents

Input Files - Methane

• initial-positions.py - Simple python script which generates initial guesses for the hydrogen positions based on known methane geometry
• methane.in - QE input file for methane, set to use Hellmann-Feynman theorem to iterate ion positions to solve methane. Lattice is large to prevent methane/methane interaction
• C.UPF - Atomic orbital data for carbon to use as initial SCF guess
• H.UPF - Atomic orbital data for hydrogen to use as initial SCF guess

Output Files/Directories - Methane

• methane.out - QE output file giving final methane binding energy and atomic positions
• tmp - Temporary directory which stores the solved e-density