rxn1_2.ltor.rate = 1e-19;
rxn1_2.rtol.rate = 1e-4;
rxn1_2.rxn_grp = 1;
 
rxn3_4.ltor.rate = 1.0;
rxn3_4.rtol.rate = 1e-30;
rxn3_4.rxn_grp = 1;
 
rxn5_6.ltor.rate = 1e-30;
rxn5_6.rtol.rate = 1e-2;
rxn5_6.rxn_grp = 1;