[lammps-users] question on fix ave/correlate

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1

Hello, Steve?
First many thanks for all your previous helps really.

  1. I’ve performed fix ave/correlate based on sample file but it showed an error message as follows.

ERROR: Compute ID for fix ave/correlate does not exist

the relevant code for it is as follows.

variable Jx equal c_flux1/vol
variable Jy equal c_flux2/vol
variable Jz equal c_flux3/vol
fix JJ all ave/correlate $s $p $d &
c_flux1 c_flux2 c_flux3 type auto file J0Jt.dat ave running
variable scale equal 1./$kB/$T/$T/$V*$s*$dt1.6e3
variable k11 equal trap(f_JJ3)$scale
variable k22 equal trap(f_JJ4)$scale
variable k33 equal trap(f_JJ5)$scale

What’s wrong with it?
What should I do for it?

  1. Incidentally asking, should I use flux1 instead of flux[1] in LAMMPS of the latest version?
    I know that I should use flux[1] in that of older version.
    In addition, there is no description for JJ in detail.
    What does it mean in vector form?
    That is, would you let me know what F_JJ1, F_JJ2, and F_JJ6 mean respectively, please?

Best regards,

Luke

2

sorry - all of this is bad-formatted HTML on the doc
page for compute heat/flux. Please look at the current
doc page on the WWW site - all the square and curly
braces in the various commands should now appear properly ...

Steve

2010/8/27 JhonY. I. <[email protected]...>:

3

Thanks you, Steve.
By the way, it is still hard to know fully what JJ in ave/correlate command mean.

  1. would you let me know what JJ (ID of fix av/correlate) in ave/correlate command means in detail, please?

  2. Does it have vector or array form?
    Then, what does JJ[1],JJ[2],JJ[3]… or array of JJ mean?
    What size of it?

  3. I think trap() of the sample code is performed every time.
    Is it possible we integrate JJ[3] every five step rather than every step?
    More generally speaking, can we perform variable command (or compute command) with some interval steps (using “if(i%5)==0” etc.)?

Best regards,

Luke

4

This is explained in detail at the bottom of the fix ave/correlate
doc page. I also suggest you dump it to a file
and stare at the values for a short run, and you will figure
it out.

Steve

2010/9/1 JhonY. I. <[email protected]...>: