The Fire algorithm (GOMethod = fire) uses a molecular dynamics
integrator to compute new geometries and velocities.
Currently, two integrator schemes can be selected
Options:
euler:
The Explicit Euler method.
verlet:
The Velocity Verlet algorithm.
semi_implicit_euler:
Semi-implicit Euler integration, see J. Guénolé, et al. Computational Materials Science 175 (2020) 109584.