[gmx-users] Unexpected results arising from T- and P-coupling methods

[英雄不再寂寞]

Dear gmxers,
   According to my recent practice, we find that the Berensen methods for T- and P- coupling can yield reasonable averaged density as a function of temperature, but when the v-rescale method and the Parrinello-Rahman method are employed for T- and P- coupling, somewhat unexpected results (i.e. density at higher temperature is bigger than that at lower tempearature) are obtained. Generally, the latter setup is considered to be prefered to the former one in simulating realistic ensemble. I am using gmx-4.5.3, and previously I have also performed one similar work using 4.0 which can generate expected results using the latter setup. I wonder if this version 4.5.3 has some bugs in calculating T and P, and are they dealt with in 4.5.4? Please give me some hints.
  
 Yours sincerely,
 Chaofu Wu, Dr.
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  Department of Chemistry and Materials Science, Hunan University of Humanities, Science and Technology, Loudi 417000, the People’s Republic of China (P.R. China)
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