Problem in Potential energy minimization curve

GROMACS version:
GROMACS modification: Yes/No
I have done energy minimization of ssDNA but the Potential energy curve shows steep drop.

Hi,
during energy minimization, the system is driven toward a minimum in energy. Thus it is expected that the energy will decrease. Usually it decreases fast in the first step, and then the curve becomes more flat.
Best regards
Alessandra