package require psfgen  
topology top_all27_prot_na.rtf
pdbalias residue G GUA
pdbalias residue C CYT
pdbalias residue A ADE
pdbalias residue T THY
pdbalias residue U URA
pdbalias residue HIS HSE
pdbalias atom ILE CD1 CD
foreach bp { GUA CYT ADE THY URA } {
     pdbalias atom $bp "O5\*" O5'
     pdbalias atom $bp "C5\*" C5'
     pdbalias atom $bp "O4\*" O4'
     pdbalias atom $bp "C4\*" C4'
     pdbalias atom $bp "C3\*" C3'
     pdbalias atom $bp "O3\*" O3'
     pdbalias atom $bp "C2\*" C2'
     pdbalias atom $bp "O2\*" O2'
     pdbalias atom $bp "C1\*" C1'
  }
segment U {pdb comp2p.pdb}
coordpdb comp2p.pdb U 
guesscoord 
writepdb comp2.pdb 
writepsf comp2.psf