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From: |
Santosh Mogurampelly <vedhava@...24...> |

Date: |
Tue, 29 Aug 2017 16:39:08 -0400 |

You should subtract the *average* of total energy from particle's total energy for the HCACF to decay to zero.

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On Tue, Aug 29, 2017 at 3:06 PM, Daksha, Chaitanya Mrityunjay <daksha@...2437...> wrote:

Dear LAMMPS Users,

I am trying to calculate the thermal conductivity of a (10,10) CNT that is 5 nm in length using the Green-Kubo formalism. I modified the liquid Argon LAMMPS thermal conductivity example for CNT. First, I equilibrated the CNT structure at 300K, and then I ran the simulation to get the heat flux, heat current auto correlation function (HCACF) and thermal conductivity. To plot the HCACF, I averaged columns 4, 5, and 6 in the ‘J0Jt.dat’ file for every 1000 timesteps (which is my dump interval).

Currently I am having two problems -

- The HCACF does not decay to zero. I have tried running the simulation for up to 1200 ps, but the HCACF still did not decay to zero.
- The thermal conductivity value I attain differs based on the correlation length parameter I use in the ‘fix ave/correlate’ command. Should the conductivity be independent of correlation length? If not, then how should I determine the appropriate correlation length?

I checked the LAMMPS email archive, but I was not able to find anything specific to my issues. Attached is the LAMMPS script, as well as other input data files. There is also a graph of the HCACF over time attached.

I would appreciate any insights as to why the HCACF does not decay to zero.

Thank you,

Chad Daksha

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**Follow-Ups**:**Re: [lammps-users] Issues with CNT Thermal Conductivity Calculations***From:*"Daksha, Chaitanya Mrityunjay" <daksha@...2437...>

**References**:**[lammps-users] Issues with CNT Thermal Conductivity Calculations***From:*"Daksha, Chaitanya Mrityunjay" <daksha@...2437...>

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