NVE

[reza_namakian1]

Dear VASP Team,

I have been testing a structure relaxation technique dubbed “NVERE” for the NVE ensemble relaxation engine:

https://doi.org/10.1039/C7CP04838F

The existing LAMMPS commands provided by the authors seem very straightforward to implement without any extra effort, and after testing, I found it works surprisingly well.

I was wondering if there is any chance to do the same trick in VASP. I have pasted the LAMMPS commands the authors provided, in below.

Thanks!

Reza.

Code: Select all

variable p1 equal "step"
variable p2 equal "ke"
variable p3 equal "pe"
variable p4 equal "etotal"
fix 1 all nve
fix out all print 1 "${p1} ${p2} ${p3} ${p4}" file res-nve.txt screen
no
run 1
variable tmp equal ke
variable ke_old equal ${tmp}
label loop
variable a loop 30000
run 1
variable tmp equal ke
variable ke_new equal ${tmp}
if "${ke_new} < ${ke_old}" then &
"velocity all set 0.0 0.0 0.0 sum no units box" &
"variable ke_old equal 0" &
else &
"variable tmp equal ke" &
"variable ke_old equal ${tmp}"
next a
jump SELF loop
print "ALL DONE"

[michael_wolloch]

Hi Reza,

I am unfamiliar with advanced MD techniques and had not heard about the NVERE approach before. So far, nothing like this has been implemented in VASP directly.

However, since version 6.5.0, we provide a library, which allows you to use VASP machine learned force fields (MLFFs) within LAMMPS!

Since the NVERE algorithm seems to work with "long" trajectories, I assume that the use of MLFFs is on your mind anyhow, so this interface to LAMMPS in combination with the commands you already prepared could be an easy way to get this to run for you.

Let me know if this approach sounds reasonable,
all the best, Michael