Before revision:  The stacking interactions of the methyl groups are observed to globally inhibit CG:CG step overtwisting while simultaneously softening the modes locally via potential energy modulations that create metastable states  .
After revision:  The stacking interactions of the methyl groups are observed to globally inhibit CG:CG step overtwisting while simultaneously softening the modes locally via potential energy modulations that create metastable states . Additionally, the indirect effects of the methyl groups on possible base-pair steps neighboring CG:CG are observed to be of comparable importance to their direct effects on CG:CG .