`Time_step <value>`

Time step in femtoseconds. This is the long time step in case of the double time step algorithm.

Default: 2 fs.

`Number_steps <number>`

How many MD steps to run.

`Double_timestep <number>`

Double time step algorithm by Tuckerman et al.

`<number>`

is the number of short time steps in one long. The keyword cannot be used simultaneously with`Constrain`

.`Constrain <toler> <i_1> <i_2> <i_3> .... <i_ntypes>`

Use SHAKE algorithm to constrain the bond lengths. The option cannot be used with

`Double_timestep`

.`<toler>`

is the tolerance level.`<i_1> <i_2> ... <i_ntypes>`

are numbers 0 or 1, which specify whether (1) or not (0) to apply constraints to molecules of each species.`R_cutoff <value>`

Cut-off (in Å) for the Lennard-Jones and real-space part of the electrostatic forces.

Default: 12 Å

`R_short <value>`

Cut-off (in Å) for Lennard-Jones forces computed each short-time step (has an effect only in double-time step algorithm)

Default: 5 Å

`Neighbour_list <number>`

Update the list of neighbors (Verlet list) every

`<number>`

stepsDefault: 10

`Electrostatics <type> [<A> <B>]`

How to treat electrostatics

`<type>`

may be Ewald (default), RF (reaction field) and CutoffFor Ewald: A is , where is the Ewald convergence parameter. Precision of the real-space Ewald part is determined by . defines the number of terms in the reciprocal part. It cuts the reciprocal series when expression in the

*exp*of the reciprocal part exceeds . Recommended values A = 2.5 - 3; B = 7 - 10.For reaction field, A is the dielectric permittivity and B is the Debye screening length in Å. Setting the Debye length to 0 means an infinite Debye length, i.e non-conducting solution.

If

`<type>`

is ``Cutoff'', parameters and are not necessary, and no special treatment of electrostatic forces out of takes place.Default: Ewald method with A=2.8 and B=9.

`Cut_forces <value>`

If this option is specified and the absolute force acting on any atom exceeds the specified

`<value>`

, the force will be cut to this level while maintaining the direction. The value is given in Å and has a sense of the maximum allowed additional displacement during one time step ( F*dt**2/m ) caused by this forceDefault: Do not cut forces

`Bind_atoms <file> <deviation>`

If this keyword is specified, atoms defined in file

`<file>`

will be bound to corresponding positions (given in the same file) by a harmonic potential with characteristic deviation given by`<deviation>`