# aimd

Performs ab initio molecular dynamics simulation. This command can appear in the global context.

### Options

integrator

Specify the algorithm for integrating the equations of motion.

• The type is string
• The default is velocity verlet
• The value must be one of:
n_steps

Specify the number of integration steps.

This option is mandatory.

• The type is int
• There is no default value.
• The value must be nonnegative
name

Specify the name of a set of results.

This option is deprecated.

• The type is string
• There is no default value.
output_coordinates

Specify name of the xyz file containing the coordinates from snapshots of the simulation.

• The type is string
• The default is coordinates
output_energies

Specify name of the txt file containing the energies from snapshots of the simulation.

• The type is string
• The default is energies
output_forces

Specify name of the xyz file containing the forces from snapshots of the simulation.

• The type is string
• The default is forces
output_metadynamics

Specify name of two metadynamics output files:

1. with "_bias.txt" suffix, and contains collective variable and instantaneous biasing potential info,
2. with "_free_energy.txt" suffix, and contains a series of free energy surface scans every every free_energy_scan_steps MD steps.

• The type is string
output_restraint

Specify name of the xyz file containing the restraint potential and forces from snapshots of the simulation.

• The type is string
• The default is restraints
output_steps

Number of steps that elapse between outputting simulation information, which includes energies, coordinates, velocities, and forces, etc.

• The type is int
• The default is 1
• The value must be positive
output_velocities

Specify name of the xyz file containing the velocities from snapshots of the simulation.

• The type is string
• The default is velocities
print_level

Print level.

• The type is int
• There is no default value.
• The value must be one of:
• -2 - No output
• -1 - Minimum output
• 0 - Output that doesn't scale with system size
• 1 - Output that scales linearly with system size
• 2 - (Debugging) output that scales quadratically with system size
• 3 - (Debugging) output that scales cubically with system size
save_steps

Whether to save the steps to the results.

If true, output_steps controls the number of steps that elapse between saving a step. The step information contains: energies, coordinates, velocities, and forces.

• The type is bool
• The default is false
save_to_file

Whether to write the simulation results to files.

• The type is bool
• The default is false
time_step

Specify the time step for integration.

• The type is quantity
• The default is 1.0 fs
• The value must be positive