ex04_reset_calculator.py

"""Example showing how to apply VaspInteractive calculators for different atoms
   In the no-context (classic) mode, you need to manually finalize the VaspInteractive calculator
   while in the context mode less coding is needed
"""
import numpy as np
import os
import tempfile

from ase.build import molecule
from ase.optimize import BFGS

from vasp_interactive import VaspInteractive
from ase.calculators.vasp import Vasp

# Methane and ethylene molecules
_m1 = molecule("CH4", vacuum=5, pbc=True)
_m2 = molecule("C2H4", vacuum=5, pbc=True)


def _dyn_run(atoms, calc, fmax=0.05):
    """run dynamics on atoms"""
    atoms.calc = calc
    dyn = BFGS(atoms)
    dyn.run(fmax=fmax)
    return


def using_context():
    """Using VaspInteractive in context mode will automatically
    reset the calculator
    """
    print("*" * 40)
    print("Running VaspInteractive in context mode")
    print("*" * 40)

    m1 = _m1.copy()
    m2 = _m2.copy()

    with tempfile.TemporaryDirectory() as tmpdir:
        calc = VaspInteractive(
            ismear=0,
            xc="pbe",
            kpts=(1, 1, 1),
            directory=tmpdir,
        )
        # Methane
        with calc:
            _dyn_run(m1, calc)
            print(f"Relaxation of methane: {calc.steps} steps")
            print("Final energy: ", m1.get_potential_energy())

        # Ethylene
        with calc:
            _dyn_run(m2, calc)
            print(f"Relaxation of ethylene: {calc.steps} steps")
            print("Final energy: ", m2.get_potential_energy())

    print("")


def no_context():
    """Using VaspInteractive in backward-compatible approach
    In this case user need to finalize and reset the calculator
    """

    m1 = _m1.copy()
    m2 = _m2.copy()

    print("*" * 40)
    print("Running VaspInteractive in backward-compatible mode")
    print("*" * 40)
    with tempfile.TemporaryDirectory() as tmpdir:
        calc = VaspInteractive(
            ismear=0,
            xc="pbe",
            kpts=(1, 1, 1),
            directory=tmpdir,
        )
        # Methane
        _dyn_run(m1, calc)
        calc.finalize()
        print(f"Relaxation of methane: {calc.steps} steps")
        print("Final energy: ", m1.get_potential_energy())

        # Ethylene
        calc.reset()
        _dyn_run(m2, calc)
        calc.finalize()
        print(f"Relaxation of ethylene: {calc.steps} steps")
        print("Final energy: ", m2.get_potential_energy())

    print("")


if __name__ == "__main__":
    using_context()
    no_context()