Environmental Engineering Reference
In-Depth Information
Figure 1.8
Temperature profile with different number of layers (NL) of
Berendsen heat bath applied.
[40-43]. Therefore, in the following section, we mainly concentrate
on the parameter effectof bothNH and Langevin heat bath.
From the calculated heat flux and temperature gradient, we
can obtain the thermal conductivity. From Fig. 1.6d, it is obvious
that with Langevin heat bath, one can obtain a consistent result
regardless of the number of heat bath layers applied. However, due
totheexistenceofLEMandthedeterministicnatureofNHheatbath,
multiple heat bath layers are required in order to get a consistent
result. In both NH and Langevin heat bath, the calculated thermal
conductivity converges to a constant when NL
≥
3. However, the
convergedvaluesofthermalconductivityaredifferentwithdifferent
heatbaths.Moreover,thereisafreeheatbathparameter,
τ
/
λ
,which
effectively controls the strength of noise (response time in NH heat
bath/dissipaterateinLangevinheatbath).Sincewefixtheheatbath
parameter inthefirstpartofthissection, whetherthechoiceoffree
parameterindifferentheatbathisequivalenttoeachotherandhow
it can influence the calculated thermal properties are yet not clear.
In the following part, we fix the heat bath temperature at 310 K and
