tblite-fit.1.adoc

tblite-fit(1) Manual Page

Name

tblite-fit - Optimize tight-binding parameters

Synopsis

tblite fit [options] param input

Description

Takes the name of the starting parameter file as first positional argument and an input file for the settings of the run as second positional argument. A starting parameter file can be produced using the tblite-param(1) command.

Input file

The input file is provided in TOML format it contains the input to the optimization algorithm and the setup for the evaluation of the data set.

key	description	type
max-iter	Maxium number of iterations in the optimization	integer
trust-rad	Initial trust radius for performing steps	real
method	Optimization method to be used, available optimizers are newuoa	string ("newuoa")
relative	Use relative parameter optimization instead of absolute	boolean
script	Command to invoke the script to evaluate the data set	string
data-file	Name of the file to read the data from used to calculated the objective function	string
param-file	Name of the file to write the parameters of the current iteration to	string
mask	Contains the selection of the parameters to fit.	table

The mask table allows to select which parameters are part of the fit. Generally, all keys that take real values can be toggled in the mask. To enable a parameter group in the element records, add the respective table name. Possible parameter groups are hamiltonian, dispersion, repulsion, halogen, charge, thirdorder, and multipole. Only elements present in the element table will be included in the fit. Individual entries can be toggled by adding their key to the subtable.

Example

Settings for fitting carbon and hydrogen parameters, the slater exponent of the halogen atom is kept fixed to starting value.

max-iter = 100
damping = 0.1
trust-rad = 0.1
method = "newuao"
relative = true
script = "./run.sh"
data-file = ".data"
param-file = "fitpar.toml"

[mask]
hamiltonian = {}
dispersion = {}
repulsion = {}
charge = {}
thirdorder = {}
multipole = {}
[mask.element]
H = {slater=[false]}
C = {}

Script

To make the fitting procedure flexible, the module will not attempt evaluate data sets itself but invoke a user provided script. The user provided script line is run for each fit iteration. Before invoking the script the module will emit the current parametrization data to the file provided in param-file. After the iteration the module will read the reference data and actual data from the file specified in data-file. The objective function is calculated as root mean square deviation from all entries in the data file.

Environment variables

The script will get information about the current run passed by environment variables.

TBLITE_EXE

Path to the tblite(1) executable

TBLITE_OUT

Name of the data file which will be read by the optimizer to determine the objective function

TBLITE_PAR

Name of the file containing the current set of parameters. This file must be read by the program used to evaluate the tight-binding method.

Options

--dry-run

Do not run start the fitting procedure

--copy file

Write the full representation of the input to file, all defaults will be filled in and the mask expanded.

-v, --verbose

Increase verbosity of printout

-s, --silent

Reduce verbosity of printout

--version

Prints version number and citation

--help

Show this message

Command line arguments can be read from an indirect file / response file by specifying the file with @name in the command line. Each line in the file is interpreted as command line argument, shell like escape sequences are not available. The file can contain further @name inputs. If the file cannot be the argument is used literally.

See also

tblite(1), tblite-param(1)