Dear,
When I use fix langevin command for simulation, I got a big fluctuation of temperature. How can I deal with it?
Thanks in advance.
ps. equ.2 data and my in code is attached
timestep 0.0025
fix 1 all nve
fix 2 all langevin 1.2 1.2 0.1 8997959
Step Temp E_pair E_mol TotEng Press
682000 1.1813238 -1.9479968 10.463065 10.277578 -0.0028082638
682100 1.3605725 -1.9198693 10.264759 10.374835 0.013336179
682200 1.0541333 -1.8934996 10.353356 10.032601 0.00080767719
682300 1.1860909 -1.9107381 10.304787 10.163672 0.0028110943
682400 1.2195236 -1.9486065 10.306285 10.177182 0.00035344691
682500 1.1935267 -1.9291794 10.344393 10.19593 0.0052118852
682600 1.1880815 -1.9056029 10.399298 10.266287 0.014397005
682700 1.281212 -1.9225348 10.424656 10.413662 0.012786953
682800 1.2391557 -1.9139822 10.327088 10.261899 0.0034293389
682900 1.2360046 -1.873337 10.345818 10.316574 0.0082683393
683000 1.2536229 -1.9428119 10.332244 10.259811 0.0035923803
683100 1.1537768 -1.9056544 10.332727 10.148483 0.0026369962
683200 1.1619582 -1.948723 10.411466 10.19636 0.00020657652
683300 1.3740658 -1.9150471 10.443051 10.578081 -0.00018655696
683400 1.2334929 -1.8903964 10.290171 10.240119 0.0066328602
683500 1.1758241 -1.9547285 10.419223 10.218799 0.00014986566
683600 1.290522 -1.931247 10.421178 10.415362 0.0028062044
683700 1.1397199 -1.9258095 10.437713 10.212341 0.0018401927
683800 1.2815716 -1.9740645 10.399087 10.3371 -0.00022648225
683900 1.1154741 -1.9905906 10.501903 10.175575 0.0036773978
684000 1.2060758 -1.9872286 10.479343 10.291553 0.0028098836
684100 1.3502226 -1.9785129 10.376311 10.412302 -0.0011047628
684200 1.1210954 -1.9650313 10.379869 10.087488 0.0041068046
684300 1.1592034 -1.9674761 10.35418 10.11621 -0.00093368941
684400 1.2427922 -2.005159 10.41051 10.259571 -0.00033066485
684500 1.364549 -1.9827978 10.331429 10.38451 0.0063787954
684600 1.1571749 -1.9126419 10.490597 10.304435 -0.0034519274
684700 1.2221167 -1.8453262 10.422656 10.400702 0.0056092771
684800 1.1864322 -1.9167798 10.370001 10.223353 0.00056258221
684900 1.2856146 -2.0126989 10.367634 10.273045 0.0030351985
685000 1.3125382 -1.9322063 10.37264 10.398712 -0.0026895002
685100 1.2591685 -1.9715689 10.38354 10.290624 0.0012774375
equ.in (1.63 KB)
equ.2 (26.9 KB)
Dear,
When I use fix langevin command for simulation, I got a big fluctuation of temperature though I have run 10^6 steps.
If I use fix temp/berendsen 1.2 1.2 0.6, it have a small fluctuation,but when I turn to Nose-Hoover thermostat after many steps in berendsen thermostat, the big fluctuation appears again ( fig.1 is attached)
How can I deal with it?
Thanks in advance.
ps. equ.2 data and my in code is attached
timestep 0.0025
fix 1 all nve
fix 2 all langevin 1.2 1.2 0.1 8997959
Step Temp E_pair E_mol TotEng Press
682000 1.1813238 -1.9479968 10.463065 10.277578 -0.0028082638
682100 1.3605725 -1.9198693 10.264759 10.374835 0.013336179
682200 1.0541333 -1.8934996 10.353356 10.032601 0.00080767719
682300 1.1860909 -1.9107381 10.304787 10.163672 0.0028110943
682400 1.2195236 -1.9486065 10.306285 10.177182 0.00035344691
682500 1.1935267 -1.9291794 10.344393 10.19593 0.0052118852
682600 1.1880815 -1.9056029 10.399298 10.266287 0.014397005
682700 1.281212 -1.9225348 10.424656 10.413662 0.012786953
682800 1.2391557 -1.9139822 10.327088 10.261899 0.0034293389
682900 1.2360046 -1.873337 10.345818 10.316574 0.0082683393
683000 1.2536229 -1.9428119 10.332244 10.259811 0.0035923803
683100 1.1537768 -1.9056544 10.332727 10.148483 0.0026369962
683200 1.1619582 -1.948723 10.411466 10.19636 0.00020657652
683300 1.3740658 -1.9150471 10.443051 10.578081 -0.00018655696
683400 1.2334929 -1.8903964 10.290171 10.240119 0.0066328602
683500 1.1758241 -1.9547285 10.419223 10.218799 0.00014986566
683600 1.290522 -1.931247 10.421178 10.415362 0.0028062044
683700 1.1397199 -1.9258095 10.437713 10.212341 0.0018401927
683800 1.2815716 -1.9740645 10.399087 10.3371 -0.00022648225
683900 1.1154741 -1.9905906 10.501903 10.175575 0.0036773978
684000 1.2060758 -1.9872286 10.479343 10.291553 0.0028098836
684100 1.3502226 -1.9785129 10.376311 10.412302 -0.0011047628
684200 1.1210954 -1.9650313 10.379869 10.087488 0.0041068046
684300 1.1592034 -1.9674761 10.35418 10.11621 -0.00093368941
684400 1.2427922 -2.005159 10.41051 10.259571 -0.00033066485
684500 1.364549 -1.9827978 10.331429 10.38451 0.0063787954
684600 1.1571749 -1.9126419 10.490597 10.304435 -0.0034519274
684700 1.2221167 -1.8453262 10.422656 10.400702 0.0056092771
684800 1.1864322 -1.9167798 10.370001 10.223353 0.00056258221
684900 1.2856146 -2.0126989 10.367634 10.273045 0.0030351985
685000 1.3125382 -1.9322063 10.37264 10.398712 -0.0026895002
685100 1.2591685 -1.9715689 10.38354 10.290624 0.0012774375
equ.in (1.63 KB)
equ.2 (26.9 KB)
fig.1.eps (13.4 KB)
Try a different damping (time) constant.
Steve
The mean T is correct - I'd try a differnent damping constant.
If your system is small, fluctuations are inevitable.
Steve