DFT calculation for a long sequence of ss-DNA

Dear All,
Good day! Do you have suggestions about the possibility of DFT (QM) calculation for full sequence of ss-DNA (e.g. 50 mers) through DMol3 Discovery Studio? Does DMol3 capable to simulate the DFT for a long sequence of DNA ?
I tried many times and still failed. I was using CHARMm ff for minimization and GGA (RPBE) along with DN basis set for DFT calculation.
Please be advised and thanks in advance for your help.

Warm regards,