Reproduce IL GEMC simulations and time efficiency

Hi Developers,

I hope you're doing well as we just before the spring.

I'm trying to reproduce the results of CO2 solubility in [c4mim][tf2n] bulk and confined system.
Your paper:DOI: 10.1021/acs.iecr.7b00763

So far I met two issues:
1. The CO2 solubility in 2nm IL confined system exchange with pure CO2 gas phase, i.e. GEMC with CO2 in box2 at 100 bar. I attach the output properties, the number of CO2 in the liquid phase is around 130, and the mole fraction of co2 should be 130/(250+130)=0.34, which is different from Figure 3.
I've tried to solve this for several weeks, but still no head at all. Can you help me to see what's going wrong?

2. It costs 2 hrs to run 40K MC steps GEMC simulation with my configuration, and it will cost me ~ 400 days if I run 200 M MC steps used in this paper. The simulation is running on 28 cores on one E5-2680v4@2.40GHz,broadwell node. Is there any way I can speed it up, like modify the input file and run simulation on multiple nodes?

I'm not sure if I make everything clear, please let me know if you need any info.

Thanks so much,
Jiaming