# potfit wiki

open-source force-matching

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parameters

# Parameters

Following is a complete list of all potfit parameters, together with a short description of their meaning, and indications when they are needed. Floating point numbers should be given in decimal notation. Vectors are given as a list of components, separated by spaces or tabs (all on one line).

An asterisk (*) marks required parameters.

 parameter name parameter type default value short explanation

### main parameters

 ntypes* integer (none) number of atom types (types vary in [0,..,ntypes-1])

### file names

 config* string (none) file with atomic configurations in force format, see Configurations
 startpot* string (none) file name containing the starting potential, see Potential files
 tempfile* string (none) file name for temporary (intermediate) potentials, see Tempfile
 endpot string \$startpot_end file name for final potential, see Potential files
 imdpot string (none) file name prefix for imd potentials, see IMD
 plotfile string (none) file name for plotting potential, see Plotfile
 flagfile string (none) file, whose presence terminates the current fit, see Flagfile

### general options

 write_pair boolean 0 write radial pair distribution, see Pair distribution
 write_lammps boolean 0 write potential in LAMMPS format, see Lammps
 cell_scale float 1.0 rescale all cells, see cell_scale

### Minimization options

 opt boolean 0 whether or not to perform an optimization
 eng_weight* float (none) weight of energy in minimization, see Algorithms
 stress_weight float (none) (* if compiled with stress) weight of stress in minimiziation, see Algorithms
 anneal_temp float 1. starting temperature for simulated annealing, set to 0 to skip simulated annealing, see Simulated Annealing
 evo_threshold float 1. stop the evolutionary algorithm if the difference in the population is smaller than this, set to zero to skip evo, see Differential Evolution
 d_eps float 0.0 error margin for powell minimization - if the improvement is smaller, the optimization is stopped, see Method of Least Squares
 seed integer 4 seed for random number generator
 apot_punish float 0. scaling factor for apot punishments, this does not affect out-of-bounds punishment, see Analytic potentials/Punishments

### options only for tabulated potentials

 plotpointfile* string (none) file name for plotting the sampling points, see Plotpointfile
 distfile string (none) file name for distribution file (* with compile option 'dist'), see Distfile
 maxchfile string (none) file with maximal permissible changes for each parameter, see Maxchfile

### options only for analytic potentials

 plotmin float 0.0 starting point for plotting potentials, see Plotfile
 enable_cp boolean 0 whether or not to include chemical potentials, see Pair Potentials

### options for output

 imdpotsteps integer 1000 number of points in each function in imd and lammps potential files, see IMD / Lammps
 output_prefix string (none) prefix for various output files, see Output
 extend float 2. how many steps should the imd potentials be extrapolated, see IMD

### parameter for option coulomb

 dp_cut float 10 cutoff-radius for electrostatic interactions, doesn't depend on other pair-function-radii.

### parameters for option dipole

 dp_tol float 1.e-7 dipole iteration precision.
 dp_mix float 0.2 mixing parameter for dipole convergence during iteration.
parameters.txt · Last modified: 2014/01/23 10:46 by daniel