MC3 lipid CpHMD parametrization: calibration run at lambda 0.20 (buffer 0.80)

Calibration run for the constant pH MD parametrization of the ionizable lipid DLin-MC3-DMA (MC3), following the phbuilder workflow: a single MC3 molecule in water with ions and a buffer particle, position-restrained, with lambda fixed at 0.20 (buffer 0.80), 1 ns, used to fit the dV/dlambda correction (Fig. S19 of 'When lipids embrace RNA: pH-driven dynamics and mechanisms of LNP-mediated siRNA delivery').