potfiles:main
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potential_files [2013/02/28 13:24] – created daniel | potfiles:main [2018/09/22 14:29] – daniel | ||
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- | {{TOC_right}} | + | ~~NOTOC~~ |
- | The interactions | + | ====== Potential files ====== |
+ | ---- | ||
+ | The interactions supported by //potfit// are defined in terms of tabulated functions, given by analytic parameters | ||
- | === Potential File Header === | + | 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. |
- | The header is comparable to headers | + | For potentials implemented |
- | ## this is just a comment line | + | ==== Potential File Header |
- | #F 3 n | + | |
- | #T < | + | |
- | #C Mg Zn | + | |
- | #I 0 1 .... n entries (this line is optional) | + | |
- | #G 2 3 .... n entries (this line is optional) | + | |
- | ## this is another comment line | + | |
- | #E this is the very last header line | + | |
- | Header lines start with the hash character '#' | + | The header format |
- | The line starting with #T specifies the type of potential this file contains. This is very helpful if you are dealing with different potentials. <TYPE> can be PAIR, EAM, ADP or ELSTAT. | + | <code potfit> |
+ | #F < | ||
+ | #T < | ||
+ | #C <element 0> <element 1> ... | ||
+ | #I 0 1 ... n entries | ||
+ | #G 2 3 ... n entries | ||
+ | #E | ||
+ | </code> | ||
- | The line I defines whether a whole potential function should be kept constant during a force matching run. Each digit corresponds | + | Header lines have to start with the number sign '' |
- | The line G specifies whether the gradient | + | The second character can be any of the following specifiers. Lines with unknown specifiers will be treated |
- | The line C specifies the chemical elements the potentials belong to. Currently this line is not read for potentials, it is only given in the output to facilitate the handling | + | Not all specifiers all mandatory, some of them are optional. |
- | #F 0 12 | + | == #F == |
- | #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 | + | |
- | The order of the different | + | The mandatory format specifier ''# |
+ | It requires two arguments, | ||
+ | Valid formats are: | ||
+ | * [[potfiles: | ||
+ | * [[potfiles: | ||
+ | * [[potfiles: | ||
+ | * [[potfiles: | ||
- | === Format 0 === | + | The value for the number of potential functions needs to be the correct value for the selected potential type. |
+ | If the number of atom types in the parameter file is 2 and the potential is '' | ||
- | The potential format 0 is used for analytical potentials exclusively. All of the above apply here, except for the G line. | + | == #T == |
- | Every analytic potential | + | The optional interaction type specifier ''# |
- | type identifier | + | 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 '' |
- | | + | |
- | # rmin 1.0 | + | |
- | p_1 value min max | + | |
- | p_2 value min max | + | |
- | ... | + | |
- | The type keyword has to be followed by the [[Analytic potentials/ | + | == #C == |
- | A sample format 0 potential file for a binary | + | The line ''# |
+ | read for potentials, it is only given in the output to facilitate the handling of potential files. In | ||
+ | addition there will also be a comment on how the potentials are ordered, for the ternary | ||
+ | a header for an EAM-potential | ||
- | === Format 3 === | + | <code potfit> |
+ | #F 0 12 | ||
+ | #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 | ||
+ | </ | ||
- | 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 | + | == #I == |
- | | + | The line ''# |
+ | matching run. Each digit corresponds to one function table, so there should be n digits in total. A | ||
+ | value of '' | ||
+ | keeps it fixed. This is useful for example if a third component is to be added to a binary system | ||
+ | and only the additional potentials are to be allowed to change. | ||
- | specifying the start, end, and the number of function values in each data set. n data columns. The argument x is either the atom distance, or the host electron density. These n lines are then followed by n blocks with the function values, one for each atom type pair or atom type. The spacing of function values is computed from the begin, end, and number of function values of the corresponding table and can be different for the different data columns. | + | == #G == |
- | If the ' | + | The line ''#G'' specifies whether |
+ | or as an additional degree of freedom. Each digit corresponds to one function | ||
+ | n digits in total. The information is bit-coded, '' | ||
+ | '' | ||
+ | This does not apply to analytic potentials. | ||
- | A sample format 3 potential file for a binary system for an EAM potential is available [[Media: | + | == #E == |
- | === Format 4 === | + | The very last header line must have |
+ | a character '' | ||
- | 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 be equidistant is dropped. Arbitrarily spaced sampling points are possible, but the sampling points have to be given in order. | + | ---- |
- | Preceding | + | The order of the different potential functions for a specific potential can be found on the |
+ | corresponding | ||
- | | ||
- | | ||
- | ... | ||
- | | ||
- | Please note that < | ||
- | |||
- | 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