[gmx-users] NVE+NVE: Two groups: one with Tcouple while the other one not

[Guiyuan Mo]

Hi, 


I am modelling a box with two groups of molecule: N2 and C12H26. 
1. Initially, NVT was used for both: 

; Temperature coupling is on 
Tcoupl = nose-hoover 
tau_t = 1.0 1.0 
tc-grps = N2 nC12 
ref_t = 450 300 


2. Then I turned off the Tcoupl for nC12 (by setting tau_t = -1): 

; Temperature coupling is on 
Tcoupl = nose-hoover 
tau_t = 1.0 -1 
tc-grps = N2 nC12 
ref_t = 450 300 


What I expected was that nC12 was heated up by N2. However the system temperature would go much higher than 450K... We know this is not true. 


Does anyone can help me? Is there something wrong or needed to take care when using tau_t = -1? Thanks. 


Best, 
Mo