rna_cg1.xml

<ForceField>
  <AtomTypes>
    <Type name="0" class="ADE" element="Ar" mass="328.212"/>
    <Type name="1" class="GUA" element="Ga" mass="344.212"/>
    <Type name="2" class="CYT" element="C"  mass="304.182"/>
    <Type name="3" class="URA" element="U"  mass="305.164"/>
  </AtomTypes>
  <Residues>
    <Residue name="ADE">
      <Atom name="A" type="0"/>
      <ExternalBond atomName="A"/>
      <ExternalBond atomName="A"/>
    </Residue>
    <Residue name="ADET">
      <Atom name="A" type="0"/>
      <ExternalBond atomName="A"/>
    </Residue>
    <Residue name="GUA">
      <Atom name="G" type="1"/>
      <ExternalBond atomName="G"/>
      <ExternalBond atomName="G"/>
    </Residue>
    <Residue name="GUAT">
      <Atom name="G" type="1"/>
      <ExternalBond atomName="G"/>
    </Residue>
    <Residue name="CYT">
      <Atom name="C" type="2"/>
      <ExternalBond atomName="C"/>
      <ExternalBond atomName="C"/>
    </Residue>
    <Residue name="CYTT">
      <Atom name="C" type="2"/>
      <ExternalBond atomName="C"/>
    </Residue>
    <Residue name="URA">
      <Atom name="U" type="3"/>
      <ExternalBond atomName="U"/>
      <ExternalBond atomName="U"/>
    </Residue>
    <Residue name="URAT">
      <Atom name="U" type="3"/>
      <ExternalBond atomName="U"/>
    </Residue>
  </Residues>
</ForceField>