1.3. Run calculation command: qha run

1.3.1. How to write computational settings file

First one needs to prepare a standard input file and a YAML file specifying the computational settings, which is referred to settings.yaml here. Please refer to this website if not familiar with YAML syntax.

Here are the keys that can be recognized in settings.yaml:

• calculation: The calculation type user wants to perform. Allowed values are single, same phonon dos and different phonon dos.

• NT: Number of temperatures on the grid

• T_MIN: Desired minimum temperature to calculate, in Kelvin, default value is 0 K.

• DT: The interval between two nearest temperatures on the grid

• NTV: Number of volumes (or equivalently, pressure) on the gird

• DELTA_P: The interval between two pressures on the grid, the default value is \(0.1\) GPa

• DELTA_P_SAMPLE: Pressure-sampling interval, used for output, the default value is \(1\) GPa

• P_MIN: Desired minimum pressure to calculate, in GPa

• input: Name(s) of the input file(s).

  • In the single-configuration calculation, only the path of the file is needed,

  • In the multi-configuration calculation, the names of the inputs files and the corresponding configuration degeneracy are given in a YAML dictionary syntax.

• static_only: Whether to include the vibrational contribution in the calculation. Allowed values are True (not include) or False (include, default).

• order: Order of Birch–Murnaghan equation of state fitting, can be 3 (default), 4 or 5.

• energy_unit: Energy unit in the output file can be ry (default) or ev

• thermodynamic_properties: Which thermodynamic properties will be calculated by qha. Allowed values are

  • F: the Helmholtz free energy

  • G: the Gibbs free energy

  • U: the internal energy

  • H: the enthalpy

  • V: the volume

  • Cp: the isobaric heat capacity

  • Cv: the volumetric heat capacity

  • Bt: the isothermal bulk modulus

  • Btp: the derivative of the isothermal bulk modulus with respect to pressure

  • Bs: the adiabatic bulk modulus

  • alpha: the thermal expansion coefficient

  • gamma: the Grüneisen parameter

• target: The default value is parallel. This is a Numba package option. Allowed options are cpu (used on single-threaded CPU), parallel (used on multi-core CPU), and cuda (used on CUDA GPU). See its official documentation for help.

• results_folder: The path to store all calculated values, the default value is ./results, which is a directory named results in the same folder as the input file.

• T4FV: Temperature for \(F(T_i, V)\) plotting. By default is ['0', '300'].

• high_verbosity: Two verbosity levels are implemented in the output file, True or False (default).

1.3.2. How to make input data

The input format is as below:

After one has prepared settings.yaml and input in the same directory, just open the terminal, redirect to that directory and run:

$ qha run ./settings.yaml

then the results will be generated in the directory specified in results_folder option in settings.yaml. If the settings.yaml is not in the same directory as the input file, one has to explicitly specify the path of it on his/her computer.

1.3.3. Output

The output files’ names and their meanings are as below:

• Helmholtz free energy: f_tp_ry.txt or f_tp_ev.txt

• Gibbs free energy: g_tp_ry.txt or g_tp_ev.txt

• Enthalpy: h_tp_ry.txt or h_tp_ev.txt

• Volume: v_tp_bohr3.txt or v_tp_ang3.txt

• Pressure-specific heat capacity: cp_tp_jmolk.txt

• Volume-specific heat capacity: cv_tp_jmolk.txt

• Isothermal bulk modulus: bt_tp_gpa.txt

• Derivative of the isothermal bulk modulus with respect to pressure: btp_tp.txt

• Adiabatic bulk modulus: bs_tp_gpa.txt

• Thermal expansion: alpha_tp.txt

• Thermal Grüneisen parameters: gamma_tp.txt