The TIS section

The TIS section defines settings for TIS and RETIS simulations.

Example TIS section:
TIS settings
allowmaxlength = False
freq = 0.5
zero_momentum = False
seed = 1
aimless = True
maxlength = 20000
sigma_v = -1
rescale_energy = False

Description of keywords for the TIS section

The following keywords can be set for the TIS section:

Keyword freq

freq = float

This defines how often shooting moves are performed: It corresponds to the percentage of the TIS moves that should be shooting moves. E.g. if freq = 0.5 then 50% of the TIS moves are shooting moves. Note that if you are running a RETIS simulation, then the percentage of TIS moves will be modified by the percentage of swapping moves, e.g. the percentage of shooting moves will then be given by (1 - swapfreq) \times freq.

No default, this keyword must be specified.

Keyword maxlength

maxlength = integer

This determines the maximum length of the paths generated. Generally, this should be set so that only a few paths are longer than this value.

No default, this keyword must be specified.

Keyword allowmaxlength

allowmaxlength = boolean

If True, we the maximum length for all paths is set to the value given by the keyword maxlength. If False, the maximum length is determined at random based on the length of the current path we are shooting from.

The default is allowmaxlength = False.

Keyword zero_momentum

zero_momentum = boolean

If this keyword is set to True, then the momentum of the system is set to zero after creating random velocities for shooting. If False, this is not done.

The default is zero_momentum = False.

Keyword seed

seed = integer

This integer is a seed for the random number generator used in the TIS algorithm (e.g. when selecting a shooting point).

The default is seed = 0.

Keyword aimless

aimless = boolean

Determines if we are to do aimless shooting or not. If this is set to False, then standard deviations for velocity generation can be set by the keyword sigma_v.

The default is aimless = True.

Keyword sigma_v

sigma_v = float

This keyword can be used to set standard deviations for the random velocity generation if the keyword aimless is set to False.

The default value is sigma_v = -1.

Keyword rescale_energy

rescale_energy = float or boolean

If this keyword is set to a number, then the velocities are re-scaled so that the total energy is equal to the given number. This is useful for performing NVE simulations. If the keyword is set to False, then the energies will not be re-scaled.

The default value is rescale_energy = False.