# Dear Gromacs users about dihedral Principal Component analysis in Gromacs **URL:** \ **Category:** User discussions\ **Created:** [August 19, 2020, 3:23am UTC](https://gromacs.bioexcel.eu/t/dear-gromacs-users-about-dihedral-principal-component-analysis-in-gromacs/685 "2020-08-19T03:23:32Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![Lazaro](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/lazaro/32/93_2.png) [@Lazaro](https://gromacs.bioexcel.eu/u/Lazaro)\ **Post date:** [August 19, 2020, 3:23am UTC](https://gromacs.bioexcel.eu/t/dear-gromacs-users-about-dihedral-principal-component-analysis-in-gromacs/685/1 "2020-08-19T03:23:32Z")
GROMACS version:2020.1 GROMACS modification: No Dear Gromacs users, I am performing a Dihedral Principal Component Analysis with Gromacs, but at the end when I get the Free Energy Landscape. How could I select the bins more representative from the trajectory from shamlog-1,2.log file? Lets say based on the energies for example or the populations? In another words: is there a systematic method to select the bins? A section of the ![2020-08-19_002144](https://europe1.discourse-cdn.com/flex017/uploads/bioexcel1/original/1X/3396b101c218cf5f512186882e611f0436d7dabf.jpeg) ![2020-08-19_002248](https://europe1.discourse-cdn.com/flex017/uploads/bioexcel1/original/1X/af4833fe0f24a61d9a6feb75be788389a94cacd5.jpeg) ![2020-08-19_002144](https://europe1.discourse-cdn.com/flex017/uploads/bioexcel1/original/1X/3396b101c218cf5f512186882e611f0436d7dabf.jpeg) shamlog file would look like this: Minima sorted after energy Minimum 0 at index 301 energy 0.000 Minimum 1 at index 175 energy 0.161 Minimum 2 at index 393 energy 0.360 Minimum 3 at index 294 energy 0.520 Minimum 4 at index 400 energy 0.642 Minimum 5 at index 281 energy 0.671 Minimum 6 at index 105 energy 0.802 Minimum 7 at index 274 energy 0.812 Minimum 8 at index 219 energy 0.950 Minimum 9 at index 338 energy 1.016 Minimum 10 at index 204 energy 1.062 Minimum 11 at index 182 energy 1.155