---
name: "g_sigeps_d"
section: "1"
platform: "linux"
package: "gromacs-data"
version: "5.0.2-1"
release: "Debian 8 (Jessie)"
platforms: ["linux"]
url: "https://new.carta.tech/gmx-sigeps"
---

# g\_sigeps\_d(1)

Convert c6/12 or c6/cn combinations to and from sigma/epsilon

Part of [gmx-sigeps(1)](/gmx-sigeps/1.md).

## NAME

gmx-sigeps - Convert c6/12 or c6/cn combinations to and from sigma/epsilon

## SYNOPSIS

gmx sigeps \[-o \[\<.xvg\>\]\] \[-nice \<int\>\] \[-\[no\]w\] \[-xvg \<enum\>\]\
            \[-c6 \<real\>\] \[-cn \<real\>\] \[-pow \<int\>\] \[-sig \<real\>\]\
            \[-eps \<real\>\] \[-A \<real\>\] \[-B \<real\>\] \[-C \<real\>\]\
            \[-qi \<real\>\] \[-qj \<real\>\] \[-sigfac \<real\>\]

## DESCRIPTION

**gmx sigeps** is a simple utility that converts C6/C12 or C6/Cn combinations to sigma and epsilon, or vice versa. It can also plot the potential in  file. In addition, it makes an approximation of a Buckingham potential to a Lennard-Jones potential.

## OPTIONS

Options to specify input and output files:

**-o** *\[\<.xvg\>\] (potje.xvg) (Output)*\
     xvgr/xmgr file

Other options:

**-nice** *\<int\> (0)*\
     Set the nicelevel

**-\[no\]w**  *(no)*\
     View output **.xvg**, **.xpm**, **.eps** and **.pdb** files

**-xvg** *\<enum\> (xmgrace)*\
     xvg plot formatting: xmgrace, xmgr, none

**-c6** *\<real\> (0.001)*\
     C6

**-cn** *\<real\> (1e-06)*\
     Constant for repulsion

**-pow** *\<int\> (12)*\
     Power of the repulsion term

**-sig** *\<real\> (0.3)*\
     sigma

**-eps** *\<real\> (1)*\
     epsilon

**-A** *\<real\> (100000)*\
     Buckingham A

**-B** *\<real\> (32)*\
     Buckingham B

**-C** *\<real\> (0.001)*\
     Buckingham C

**-qi** *\<real\> (0)*\
     qi

**-qj** *\<real\> (0)*\
     qj

**-sigfac** *\<real\> (0.7)*\
     Factor in front of sigma for starting the plot

## SEE ALSO

**[gromacs(7)](/gromacs/7.md)**

More information about **GROMACS** is available at \<*http://www.gromacs.org/*\>.