Use improved gauge action in HMC (Feature #256)


Added by Christopher Pinke about 7 years ago. Updated about 6 years ago.


Status:Done Start date:22 Feb 2012
Priority:Normal Due date:
Assignee:Christopher Pinke % Done:

100%

Category:-
Target version:2012.2 Estimated time:10.00 hours

Description

For up to date simulations, one has to use an improved gauge action.

The simplest one is the tree level symanzik improved action, where one adds an object similar to the plaquette, but consisting of rectangles, to the action. Both are weighted by some factors:

S_impr = c0 * S_wilson + c1 * S_tlsym

with c0 = 1 - 8c1

For the implementation, one has to add

  • a kernel "rectangles" similar to the plaquette with appropiate testing
  • overwork the calculation of the hamiltonian to include the improved action
  • parameters c0, c1, and switches

In the end, it is easy to add additional improved gauge actions, "iwasaki" and "dbw2". For these, one just has to add different values to c0 and c1.


optimal_test_120309_2 (2.6 kB) Christopher Pinke, 13 Mar 2012 03:14 pm

optimal_test_120313 (4.6 kB) Christopher Pinke, 03 Apr 2012 03:45 pm


History

Updated by Christopher Pinke about 7 years ago

  • Target version set to 2012.2

Updated by Christopher Pinke about 7 years ago

In commit: e9f56a59 I added the parameters necessary for the tlsym gauge action.

It still has to be tested if they are read in right and the output has to be taken care of...

  • % Done changed from 0 to 10

Updated by Christopher Pinke about 7 years ago

With commits 17afef93, c7cf23f2, d4f7f99b and 38a0ccde I added all necessary functions and objects to use the tlsym improved gauge action in the HMC.

What is left to do is:

  • implement and test the kernels
  • check if HMC implementation is right
  • % Done changed from 10 to 40

Updated by Christopher Pinke about 7 years ago

With f0fb585e I have filled the corresponding functions with content and tested that the HMC runs through if tlSym gauge action is used.

However, both points from above are still valid.

  • % Done changed from 40 to 70

Updated by Christopher Pinke about 7 years ago

With 362ab38c I have debugged the tlsym related things a lot further.

The rectangles themselves are calculated correctly (on cold and hot config) and each of the 6 parts of the force ingredients (I mean the rectangles_staples function here) are also calculated correctly. I checked this with the tmlqcd code on CPU!

However, if I put together more than 2 ingredients, the result is wrong and not constant, i.e. it seems as if the compiler cannot handle the code!!!

This is of course severe, but there are good chances to break the function into a loop, for example.

After that is done, it is only left to
  • check overall force calculation
  • check the hamiltonian part
  • perform a gauge-only HMC run
  • % Done changed from 70 to 90

Updated by Christopher Pinke about 7 years ago

With ac108730 I added a working test for the rectangles functions. The problem mentioned above was solved by Matthias Bach in bad66327.
Given the same input, the rectangles and force funtions give the same output as tmlqcd (see log file).

Updated by Christopher Pinke about 7 years ago

With c6c66fdf I added everything related to the improved gauge actions.

For testing purposes I also added a switch to use pure gauge theory only (this may be advanced by neglecting more memory objects and kernels, but this has not been done yet). I tested this HMC version against tmlqcd for all 4 gauge actions (see log file).

  • File optimal_test_120313 added
  • % Done changed from 90 to 100
  • Subject changed from tlSym improved gauge action to Use improved gauge action in HMC

Updated by Christopher Pinke about 7 years ago

  • Status changed from In Progress to Done

Updated by Christopher Pinke about 7 years ago

In optimal_test_120413 I observed that the tlsmy gauge action with fermions gives the right final config, but a different dH (see #271 for the log file). This has to be investigated. The problem will most likely also arise in PGT, but was probably not seen before because I only looked at the plaquette values, not at the acc-probabilities.

  • Status changed from Done to In Progress
  • % Done changed from 100 to 90

Updated by Christopher Pinke about 6 years ago

I settled this issue in my tests 120417 and 120508.
In addition, no difference in dH could be observed in the longtime runs for the Z12 ensemble.

  • Status changed from In Progress to Done
  • % Done changed from 90 to 100

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