Dear Lammps community

I am performing numerical simulations of polymer melts under steady shear flow at different temperatures. To do that, I consider:

fix nvtshear all nvt/sllod temp 0.30 0.30 0.2 # Here, damping is defined as 100*timestep.

fix shearbox all deform 1 xy erate 0.1 remap v units box

During the deformation, I compute the temperature in two different ways:

compute newT all temp/partial 0 1 1

compute newT2 all temp/deform

Doing this, I find that (1) the temperature differs depending on what â€ścomputeâ€ť I use, and (2) there is an initial transient period where the temperature exhibits significant and unphysical oscillations.

I have made a test by considering Langevin dynamics, and I did not see these oscillations. Has anyone seen this type of behavior before?

Please, below, you can find the script I am using.

Thank you in advance for your time.

Carmen

```
===================================================
variable mytemp equal 0.30
variable seed equal 123
variable A equal 0.1
variable Ndef equal 1
variable tnvt equal 10000
variable thermodump equal 10
variable tstep equal 0.002
variable Tdamping equal 100*${tstep}
variable thermofile string thermo.dat
units lj
boundary p p p
atom_style bond
read_data initconf_T0.30
change_box all triclinic remap units box
group chain type 1
mass 1 1.0
pair_style lj/cut 2.5
pair_coeff * * 1.0 1.0 2.5
pair_modify shift yes
special_bonds fene
bond_style harmonic
bond_coeff * 555.5 0.97
comm_modify cutoff 4.0
neighbor 0.4 bin
neigh_modify every 1 delay 1 check yes
fix nvtshear all nvt/sllod temp 0.3 0.3 0.2
fix shearbox all deform 1 xy erate 0.1 remap v units box
compute newT all temp/partial 0 1 1
compute newT2 all temp/deform
variable step equal step
variable temp equal temp
variable newT equal c_newT
variable newT2 equal c_newT2
thermo_style custom step temp v_newT v_newT2
thermo ${thermodump}
fix dummy all print ${thermodump} "${step} ${newT} ${newT2}" file ${thermofile} screen no title "#1:step 2:newT 3:newT2"
timestep 0.002
run 10000
```