normal heating failed

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11 years 1 week ago - 11 years 1 week ago #1511 by syahidah
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Dear all,

thanks for all the replies before as i manage to solve most of my problems..

now i'm coarse-graining a new molecules, cremophor EL. the molecular structure is quite similar with PEG,PEO but the difference is it has 3 chains like triglycerol. i mange to do mapping and energy minimization, but when i want to proceed to heating, the "segmentation fault core dumped" keep happening after 600 steps.

attached here the files i use for the run:

cremophor.itp:

[moleculetype]
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energy minimization:
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heat.mdp:
Warning: Spoiler! [ Click to expand ]


your reply is greatly appreciated..

Thank you..

cheers,
MS

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11 years 1 week ago #1514 by djurre
Replied by djurre on topic heating failed
What might be a problem is the timestep during you heating. You use 40 fs. For many molecules this is to much (for example proteins only run at 20fs), this will be probably true for you molecules (there are some pretty high force constants). As a first short simulation after EM you might even want to go back to +/-5 fs to get things relaxed.

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11 years 1 week ago #1515 by syahidah
Replied by syahidah on topic heating failed
million thanks Djurre!managed to solve that!

so, meaning that,in equilibration run i can increase it to 20-40fs (as stated in example.mdp)?

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11 years 1 week ago #1531 by syahidah
Replied by syahidah on topic heating failed
Hi Djurre,

now i managed to complete eq stage where i used timestep = 10 fs

however, when i analysed SASA for this eq xtc file, i got all 0 for the hydrophilic values.

is it the problem came from the mdp? or itp?

Thank you..

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11 years 1 week ago #1532 by djurre
Replied by djurre on topic heating failed
I don't know how hydrophobic/hydrophylic is defined by g_sasa, but it might be that this is done by atom names in a file somewhere. In that case g_sasa just doesn't recognize Martini beads as being hydrophyllic.

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11 years 6 days ago #1537 by syahidah
Replied by syahidah on topic heating failed
Hi Djurre,

i completed equilibration part, however with 10fs time step, my production run crashed in the middle of run..as stated in .mdp file in the homepage, smaller than 20fs is not recomended. so, is is okay if i use smaller than 10fs?

for the g-sas, doe it mean my coarse-graing part is wrong?


best,
MS

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11 years 6 days ago #1538 by djurre
Replied by djurre on topic heating failed
10fs is not wrong, it is just a pity you are wasting so much computer time by using a small timestep. You might want to try and find out WHY the simulations crashes: which molecules are the first to crash and which bond/angle is the reason. If you find that out, you can tune them further.

I don't think anything is wrong about g_sas. The parameters you are feeding to it might not be correct for CG.

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