# Options¶

The configurations and options in MonteCoffee are specified in the file kMC_options.cfg, and are loaded by load_options(). The options contained in kMC_options.cfg are:

• nspecies (int): how many species are included in the simulation. This integer decides how many coverages are written to the log.
• nninteractions (int): describes the extent of the nearest neighbor interactions. Specifying 1 makes the local search for newly enabled events extent to second nearest neighbor.
• savesteps (int): Number of Monte Carlo steps between saving the .txt files.
• logsteps (int): Number of steps to skip when saving .txt files and printing the log. Setting it to 1000 makes the log output and code save every 1000th simulation step.
• tinfinity (float): The time to consider infinite. This time is set for the occurrence time of impossible events.
• savecovs (bool): If True, the site-occupations (coverages) are saved periodically to coverages.txt.
• verbose (bool): If True, prints verbose information.
• write_atoms (bool): If True, write out traj files of coverages (may have to be customized depending on the system).

Options solely related to the acceleration of kMC simulations (See accelerating):

• use_scaling_algorithm (str): If None or False, no time acceleration will be used. In the current version the following three schemes are available:

• scale_constant – scaling with a constant factor
• scale_rate – scaling based on the reaction rates
• scale_rate_constant – scaling based on the reaction rate constants
• delta (float): The reversibility tolerance for quasi-equilibrated events. This determines the criterion for whether reactions are quasi-equilibrated. Setting delta=0.25 implies that there must be no more than 25 percent difference in rates of a forward and backward reaction to deem it quasi-equilibrated.

• nf (int): A factor that separates fast and slow events. nf = 1000 means that quasi-equilibrated events are slowed down to maximally 1000 times the non-equilibrated events.

• ns (int): The frequency of adjusting barriers for quasi-equilibrated events.

• ne (int): The number of events executed for a reaction in forward and backward direction for the reaction to be considered equilibrated.