Melting in FCC, 3d, soft sphere crystals

I found that using LAMMPS' Nose-Hoover NVT setup the melting temperature was very low ( below 1E-5). To see this I simply tracked a particle for some time after starting the simulation. Why this is the case is unexplained especially since in 2D i have been getting reasonable statistics at T=0.0025.

Switching to NVE, after some short sampling at various T, it seemed that melting seemed occurred between T=0.05-0.1. I ran 2 simulations at T=0.01 and T=0.005. The following plots are the Y versus X coordinate of a SINGLE particle sampled at 10,000 timesteps from 0-4 million steps.
The MSD of the particle in the upper plot was HUGE ~27.5 !! The main contribution was ~= 26.2. It seems that T=0.005 is suitable for analysis.

NOTE: the good config (lower picture) is in the: fcc-3d/dumpfiles3/ folder and its 100 plane is extracted to the folder: fcc-3d/extractDump3/planeDump3/.