subroutine char SEGMENTS
define class charge by topo \
	sele segm name SEGMENTS .a .not atom name HT* OT* OXT end
set class sele atom name S* .and. by bond atom name S* \
     .a segm name SEGMENTS end = S
defin class charge \
     sele by resi atom name HT* .a segm name SEGMENTS .a .n resi name PRO end \
     by topo resi NTER
defin class charge \
     sele by resi atom name HT* .a segm name SEGMENTS .a resi name PRO end \
     by topo resi NTPR
defin class charge \
     sele by resi atom name OT* .a segm name SEGMENTS end \
     by topo resi COTR

defin class charge \
     sele by resi atom name OXT .a segm name SEGMENTS end \
     by topo resi CTER

!set clas sele atom name N .a by resi atom name HT* .a segm name SEGMENTS end \
!  = NH3
!set clas sele atom name C .a by resi atom name OT* .a segm name SEGMENTS end \
!  = C

define bond angle init select segm name SEGMENTS end by auto 
define dihe by topo init select segm name SEGMENTS end
define impr by topo init select segm name SEGMENTS end ! check
define impr dihe \
	select by resi atom name HT* .a segm name SEGMENTS end \
	resi NTER
define impr dihe \
	select by resi atom name OT* .a segm name SEGMENTS end \
	by topo resi COTR
define impr dihe \
	select by resi atom name OXT .a segm name SEGMENTS end \
	by topo resi CTER

define dihe impr sele by resi clas name XXXX end by guess 

! define hbond force FORCE_HBON hbond dist DIST_HBON \
 define hbond force 1000 hbond dist 1.6 \
	sele segm name SEGMENTS end 
return



!set class sele atom name HT% end HC
!set class sele atom name N* .and. by bond atom name HT* end NH3
!set class sele atom name OT% end OC