ensemble (TI)

This keyword is used to set up a equilibrium thermodynamic integration integrator. It is for testing purpose and its only differece from ti_spring keyword is that the lambda value is fixed instead of changing.


The parameters can be specified as follows:

ensemble ti_spring lambda <lambda> temp <temperature> tperiod <tau_temperature> spring <element_name> <spring_constant>
  • <temperature>: The temperature of the simulation.

  • <tau_temperature>: This parameter is optional, and defaults to 100. It determines the period of the thermostat in units of the timestep. It determines how strongly the system is coupled to the thermostat.

  • <element_name> and <spring_constant>: Specify the spring constants of elements.

  • <lambda>: The lambda value of the simulation.


ensemble ti_spring temp 300 lambda 0.3 spring Si 6 O 5

This command uses lambda value 0.3 (30% spring force and 70% original force field). The spring constant is 6 eV/A^2 for Si and 5 eV/A^2 for O.