PSF

       1 !NTITLE
 REMARKS original generated structure x-plor psf file
 REMARKS no Coulomb Charges
 REMARKS masses from Izaguirre and Hampton 2004

       4 !NATOM
       1 BUTA 1    BUTA C1   CH3    0.000000       15.0350           0
       2 BUTA 1    BUTA C2   CH2    0.000000       14.0270           0
       3 BUTA 1    BUTA C3   CH2    0.000000       14.0270           0
       4 BUTA 1    BUTA C4   CH3    0.000000       15.0350           0

       3 !NBOND: bonds
       1       2
       2       3
       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       0       0       0       0
       0       0       0       0       0       0

       1       0 !NGRP
       0       0       0