potfiles:main
Differences
This shows you the differences between two versions of the page.
Both sides previous revisionPrevious revisionNext revision | Previous revision | ||
potential_files [2013/03/01 08:15] – daniel | potfiles:main [2018/09/24 17:29] (current) – daniel | ||
---|---|---|---|
Line 1: | Line 1: | ||
+ | ~~NOTOC~~ | ||
====== Potential files ====== | ====== Potential files ====== | ||
---- | ---- | ||
- | The interactions | + | The interactions supported by //potfit// are defined in terms of tabulated functions, given by analytic parameters |
+ | |||
+ | Each potential file consists of a header and a body, just like the configurations. While the header format is the same for all supported potentials the body format is fundamentally different for tabulated, analytic and KIM potentials. | ||
+ | |||
+ | For potentials implemented in //potfit// the number | ||
==== Potential File Header | ==== Potential File Header | ||
- | The header is comparable | + | The header |
- | < | + | < |
- | ## this is just a comment line | + | #F < |
- | #F 3 n | + | #T <interaction name> |
- | #T <TYPE> | + | #C <element 0> <element 1> ... |
- | #C Mg Zn | + | #I 0 1 ... n entries |
- | #I 0 1 .... n entries | + | #G 2 3 ... n entries |
- | #G 2 3 .... n entries | + | #E |
- | ## this is another comment line | + | |
- | #E this is the very last header line | + | |
</ | </ | ||
- | Header lines start with the hash character | + | Header lines have to start with the number sign ''#'' |
- | The line starting with #T specifies | + | The second character can be any of the following specifiers. Lines with unknown specifiers will be treated like comments, but it is recommended that such lines start with two ''#'' |
- | The line I defines whether a whole potential function should be kept constant during a force matching run. Each digit corresponds to one function table, so there should be n digits in total. A value of ' | + | Not all specifiers all mandatory, some of them are optional. |
- | The line G specifies whether the gradient of the interpolation splines should be treated as fixed or as an additional degree of freedom. Each digit corresponds to one function table, so there should be n digits in total. The information is bit-coded, ' | + | == #F == |
- | The line C specifies | + | The mandatory format specifier ''# |
+ | It requires two arguments, the format itself and the number | ||
+ | Valid formats | ||
+ | * [[potfiles: | ||
+ | * [[potfiles:format3|Format 3]] - tabulated potentials with fixed spacing | ||
+ | * [[potfiles: | ||
+ | * [[potfiles: | ||
- | < | + | The value for the number of potential functions needs to be the correct value for the selected potential type. |
- | #F 0 12 | + | If the number of atom types in the parameter file is 2 and the potential is '' |
- | #C Al Pd Mn | + | |
- | ## Al-Al Al-Pd Al-Mn Pd-Pd Pd-Mn Mn-Mn Al Pd Mn Al Pd Mn | + | |
- | #I 0 0 0 0 0 0 0 0 0 0 0 0 | + | |
- | #E | + | |
- | </code> | + | |
- | The order of the different potential functions for a specific potential can be found on the corresponding potential page. | + | == #T == |
- | ==== Format 0 ==== | + | The optional interaction type specifier ''# |
- | The potential format 0 is used for analytical potentials exclusively. All of the above apply here, except for the G line. | + | Even though this line is optional, a mismatch in the string and the compiled //potfit// binary will lead to a runtime error. A //potfit// binary compiled for '' |
- | Every analytic potential has to be specified as follows: | + | == #C == |
- | < | + | The optional line ''# |
- | type identifier | + | order of chemical elements in the configuration file. In output files //potfit// will write a comment on how the potentials are ordered. For the ternary system AlPdMn this looks like this: |
- | cutoff value | + | |
- | # rmin 1.0 | + | < |
- | p_1 value min max | + | #C Al Pd Mn |
- | p_2 value min max | + | ## Al-Al Al-Pd Al-Mn Pd-Pd Pd-Mn Mn-Mn Al Pd Mn Al Pd Mn |
- | ... | + | |
</ | </ | ||
- | The type keyword has to be followed by the [[Analytic potentials/ | + | == #I == |
- | A sample format | + | The optional line ''# |
+ | matching run. Each argument corresponds to one function, so there need to be as much digits as there are potential functions. | ||
+ | and only the additional potentials are to be allowed to change. If this line is omitted all potential functions will be optimized. | ||
- | ==== Format 3 ==== | + | == #G == |
- | In a potential file in format 3, each data column has its own range and spacing. Sampling points are equidistant in the atomic distance r or (when using EAM-type interactions) electron density n. If we have n data columns, the file starts with n lines of the form | + | The optional line ''# |
+ | or as an additional degree of freedom. Each argument corresponds to one potential function, so there should be | ||
+ | n arguments in total. The information is bit-coded, '' | ||
+ | '' | ||
+ | This does not apply to analytic potentials. | ||
- | < | + | == #E == |
- | specifying the start, end, and the number | + | The last line of the header must have the ''# |
- | If the ' | + | ---- |
- | A sample format 3 potential | + | The order of the different |
- | + | corresponding | |
- | ==== Format 4 ==== | + | |
- | + | ||
- | As with potential files in format 3 each data column has its own spacing. But with potential format 4 the requirement that the sampling points | + | |
- | + | ||
- | Preceding the data columns is a header with one line per column, containing the number of sampling points in the corresponding | + | |
- | + | ||
- | < | + | |
- | r_0 | + | |
- | r_1 | + | |
- | ... | + | |
- | r_steps f(r_steps) | + | |
- | </ | + | |
- | Please note that $r_0 < r_1 < ldots < r_{steps}$ is required. The order of the columns is the same as with format 3. | ||
- | A sample format 4 potential file for a binary system (EAM potential) is available [[Media: | ||
potfiles/main.txt · Last modified: 2018/09/24 17:29 by daniel