[gmx-users] area per lipid

[Shima Arasteh]

Hi,

I am trying to simulate POPC in water in 300 K, using charmm36 FF. In order to reach appropriate area per lipid ( 63-65 Angestroms per headgroup as mentioned in articles ), I let the system to be simulated for 40 seconds. To do so, I checked the area  per lipid every 10 ns. The results of area per lipid in each step are as below:

1.
Top leaflet: 60.44  

Bottom leaflet: 59.43 


2.
Top leaflet: 61.135
Bottom leaflet: 60.11

3.
Top leaflet: 61.40  

Bottom leaflet: 60.38

4.
Top leaflet: 60.27  

Bottom leaflet: 59.27

I expected it to approaches the expected amount steadily, but why did I get such a result? How can I get to the appropriate area  per lipid? 

Would you please give me suggestions? Any suggestions would be appreciated.

Thanks in advance.


Sincerely,
Shima