PSF EXT

       3 !NTITLE
 REMARKS original generated structure x-plor psf file
 REMARKS topology toy.str 
 REMARKS segment BUTA { first NONE; last NONE; auto none  }

       4 !NATOM
         1 BUTA     1        TOY      C1       CG331    0.000000       12.0110           0
         2 BUTA     1        TOY      C2       CG321    0.000000       12.0110           0
         3 BUTA     1        TOY      C3       CG321    0.000000       12.0110           0
         4 BUTA     1        TOY      C4       CG331    0.000000       12.0110           0

       3 !NBOND: bonds
         1         2         3         2         3         4

       2 !NTHETA: angles
         1         2         3         2         3         4

       1 !NPHI: dihedrals
         1         2         3         4

       0 !NIMPHI: impropers


       0 !NDON: donors


       0 !NACC: acceptors


       0 !NNB

         0         0         0         0

       1       0 !NGRP
         0         0         0

