private Atom getCBeta(Group g1) { Atom cb = null; cb = g1.getAtom("CB"); if ( cb == null) { if ( g1 instanceof AminoAcid) { AminoAcid aa = (AminoAcid) g1; try { cb = Calc.createVirtualCBAtom(aa); } catch (StructureException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } } } return cb; }