Mass of Heat Bath for Nose-Hoover thermostat

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Mass of Heat Bath for Nose-Hoover thermostat

Date: 2020/10/26 19:31
Name: Mauro Sgroi <maurofrancesco.sgroi@gmail.com>: Dear Developers,
I'm asking here advice about the setting of the parameter NH.Mass.HeatBath.

According to Nosé http://dx.doi.org/10.1063/1.447334, Q can be selected such that

w^2 = (2gKT/Q<s^2>)

in gives the same order of magnitude as the second moment of the frequency spectrum of the velocity autocorrelation function of the physical
system. g is the number of degrees of freedom, K the Boltzmann constant, s is an additional degree of freedom which acts as an external system on the physical system of N particles,

The above approach is for me very complex: can you suggest some publication or tutorial explaining how to proceed?

Or as an alternative, are there "emprirical rules" to be used? E.g. setting Q at the same order of magnitude (or higher) with respect to the mass of the system?

Thanks a lot in advance and best regards,

Mauro Sgroi.

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Re: Mass of Heat Bath for Nose-Hoover thermostat ( No.1 )

Date: 2021/06/24 18:02
Name: Lovleen Kaur <lovleenkaurkkr@gmail.com>

Hello Mauro Sgroi
I also want to know that how to set parameters for Noose Hover MD calculations. Have you find the answer to your question?
If yes, please also suggest me that how to set parameters for Noose Hover MD calculations that will help me a lot.

Regards
Lovleen Kaur

Re: Mass of Heat Bath for Nose-Hoover thermostat ( No.2 )

Date: 2021/06/25 08:11
Name: T. Ozaki

Hi,

By an almost equivalent analysis, we may have

t ~ 2pi sqrt(Q/(2gKT))

where
t: the time period of a parameter which is an additional degree of freedom in the Nose-Hoover method
g: 3 times the number of atoms
K: Boltzmann constant
T: a given temperature of thermostat
Q: mass of the additional degree of freedom

Thus, we may expect that the thermal equilibration takes place rapidly when t is close to the time period
of the highest frequency mode (or dominant modes contributing to temperature) in a system under consideration.

If we solve the equation for Q, we have

Q = gKTt^2/(2pi^2)

Noting that for lighter elements the time period of dominant modes is a few fs, while for heavier elements
a few dozen fs, one can estimate a proper Q by the equation.

Regards,

TO

Re: Mass of Heat Bath for Nose-Hoover thermostat ( No.3 )

Date: 2021/06/25 16:52
Name: Lovleen Kaur <lovleenkaurkkr@gmail.com>

Hi,
Thank you so much for your answer.

Regards,
Lovleen Kaur

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