CCL: oplsaa force field parameter of EPON862 containing -CH2- group linked to two phenyl



Dear CCLers,
  I want to simulate an epoxy resin, EPON862, using oplsaa force field in gromacs. In the molecules, there are -CH2- group which are linked to two phenyl. In the parameter file of oplsaa force field, I can not find the suitable atom type for the C atoms. Instead, I had tried the opls_149 (CH3, toluene) or opls_148(CH2, ethyl benzene), which led to fatal errors. One of possible solution to my problem can be creating new atom type for -CH2-, but it is very hard work to optimize the parameters. So, have you happened to simulate/find such a similar molecule(there are -CH2- group which are linked to two phenyl) in the format of oplsaa force field? If yes, please kindly give me the references. Thanks a lot! 
yours sincerely,
Chaofu Wu, Dr.