[REVIEW]: CTSEG: A segment picture quantum impurity solver based on TRIQS

[editorialbot]

Submitting author: @nkavokine (Nikita Kavokine)
Repository: https://github.com/TRIQS/ctseg
Branch with paper.md (empty if default branch): 3.3.x
Version: 3.3.0
Editor: @lucydot
Reviewers: @HugoStrand, @egcpvanloon
Archive: Pending

Status

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Reviewers and authors:

Please avoid lengthy details of difficulties in the review thread. Instead, please create a new issue in the target repository and link to those issues (especially acceptance-blockers) by leaving comments in the review thread below. (For completists: if the target issue tracker is also on GitHub, linking the review thread in the issue or vice versa will create corresponding breadcrumb trails in the link target.)

Reviewer instructions & questions

@HugoStrand & @egcpvanloon, your review will be checklist based. Each of you will have a separate checklist that you should update when carrying out your review.
First of all you need to run this command in a separate comment to create the checklist:

@editorialbot generate my checklist

The reviewer guidelines are available here: https://joss.readthedocs.io/en/latest/reviewer_guidelines.html. Any questions/concerns please let @lucydot know.

✨ Please start on your review when you are able, and be sure to complete your review in the next six weeks, at the very latest ✨

Checklists

📝 Checklist for @egcpvanloon

📝 Checklist for @HugoStrand

[editorialbot]

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[editorialbot]

Reference check summary (note 'MISSING' DOIs are suggestions that need verification):

✅ OK DOIs

- 10.1103/RevModPhys.83.349 is OK
- 10.1103/PhysRevB.87.125102 is OK
- 10.1103/RevModPhys.68.13 is OK
- 10.1016/j.cpc.2015.04.023 is OK
- 10.1016/j.cpc.2015.10.023 is OK
- 10.1016/j.cpc.2017.01.003 is OK
- 10.1016/j.cpc.2012.12.013 is OK
- 10.1016/j.cpc.2018.09.007 is OK
- 10.1103/PhysRevB.105.L180404 is OK
- 10.1103/PhysRevLett.133.016501 is OK

🟡 SKIP DOIs

- None

❌ MISSING DOIs

- None

❌ INVALID DOIs

- None

[editorialbot]

Software report:

github.com/AlDanial/cloc v 1.90  T=0.06 s (2490.4 files/s, 186127.8 lines/s)
-------------------------------------------------------------------------------
Language                     files          blank        comment           code
-------------------------------------------------------------------------------
C++                             29            702            906           2215
Python                          16            258            314            939
reStructuredText                23            408            251            747
C/C++ Header                    31            369            732            736
CMake                           16            117            169            553
CSS                              2             80             20            354
YAML                             6             25              4            249
Markdown                         6             52              0            144
TeX                              1             10              0            140
HTML                             1              6              0             46
Bourne Shell                     2              6              1             21
Dockerfile                       1              3              3             12
SVG                              6              0              0              6
JavaScript                       2              0             13              2
-------------------------------------------------------------------------------
SUM:                           142           2036           2413           6164
-------------------------------------------------------------------------------

Commit count by author:

   129	nkavokine
    97	Nils Wentzell
    84	Olivier Parcollet
     9	Alexander Hampel
     6	Hao Lu
     6	Thomas Hahn
     5	Henri Menke
     2	Michel Ferrero
     1	Dylan Simon
     1	Nikita Kavokine
     1	clang_format
     1	gen_copyright

[editorialbot]

Paper file info:

📄 Wordcount for paper.md is 741

✅ The paper includes a Statement of need section

[editorialbot]

License info:

🟡 License found: Other (Check here for OSI approval)

[editorialbot]

👉📄 Download article proof 📄 View article proof on GitHub 📄 👈

[lucydot]

Hi @HugoStrand and @egcpvanloon, how are your reviews going? If you have any questions you can ask here.

[egcpvanloon]

Review checklist for @egcpvanloon

Conflict of interest

• I confirm that I have read the JOSS conflict of interest (COI) policy and that: I have no COIs with reviewing this work or that any perceived COIs have been waived by JOSS for the purpose of this review.

Code of Conduct

• I confirm that I read and will adhere to the JOSS code of conduct.

General checks

• Repository: Is the source code for this software available at the https://github.com/TRIQS/ctseg?
• License: Does the repository contain a plain-text LICENSE or COPYING file with the contents of an OSI approved software license?
• Contribution and authorship: Has the submitting author (@nkavokine) made major contributions to the software? Does the full list of paper authors seem appropriate and complete?
• Substantial scholarly effort: Does this submission meet the scope eligibility described in the JOSS guidelines
• Data sharing: If the paper contains original data, data are accessible to the reviewers. If the paper contains no original data, please check this item. The data in the figure can be generated using the code and the open source CTHYB code
• Reproducibility: If the paper contains original results, results are entirely reproducible by reviewers. If the paper contains no original results, please check this item. No original scientific results. The figure includes results on performance (see below)
• Human and animal research: If the paper contains original data research on humans subjects or animals, does it comply with JOSS's human participants research policy and/or animal research policy? If the paper contains no such data, please check this item.

Functionality

• Installation: Does installation proceed as outlined in the documentation?
• Functionality: Have the functional claims of the software been confirmed? During the review phase, we have been using ctseg in the research group, especially for single-orbital impurity models with retarded density-density interactions, and have confirmed that it works as expected.
• Performance: If there are any performance claims of the software, have they been confirmed? (If there are no claims, please check off this item.) _Performance in our tests has been good and better than the CTHYB code, consistent with Fig 1a. Detailed analysis of the performance is beyond the scope of this paper/review, since for this kind of code it depends very heavily on the physical system being simulated, the observables one is interested in as well as hardware/HPC-software used. _

Documentation

• A statement of need: Do the authors clearly state what problems the software is designed to solve and who the target audience is?
• Installation instructions: Is there a clearly-stated list of dependencies? Ideally these should be handled with an automated package management solution.
• Example usage: Do the authors include examples of how to use the software (ideally to solve real-world analysis problems).
• Functionality documentation: Is the core functionality of the software documented to a satisfactory level (e.g., API method documentation)?
• Automated tests: Are there automated tests or manual steps described so that the functionality of the software can be verified? Yes, although development of additional tests to increase the coverage and to verify correctness of the physical result would be beneficial (as discussed by @HugoStrand)
• Community guidelines: Are there clear guidelines for third parties wishing to 1. Contribute to the software 2. Report issues or problems with the software 3. Seek support

Software paper

• Summary: Has a clear description of the high-level functionality and purpose of the software for a diverse, non-specialist audience been provided?
• A statement of need: Does the paper have a section titled 'Statement of need' that clearly states what problems the software is designed to solve, who the target audience is, and its relation to other work?
• State of the field: Do the authors describe how this software compares to other commonly-used packages?
• Quality of writing: Is the paper well written (i.e., it does not require editing for structure, language, or writing quality)?
• References: Is the list of references complete, and is everything cited appropriately that should be cited (e.g., papers, datasets, software)? Do references in the text use the proper citation syntax?

[HugoStrand]

Review checklist for @HugoStrand

Conflict of interest

• I confirm that I have read the JOSS conflict of interest (COI) policy and that: I have no COIs with reviewing this work or that any perceived COIs have been waived by JOSS for the purpose of this review.

Code of Conduct

• I confirm that I read and will adhere to the JOSS code of conduct.

General checks

• Repository: Is the source code for this software available at the https://github.com/TRIQS/ctseg?
• License: Does the repository contain a plain-text LICENSE or COPYING file with the contents of an OSI approved software license?
  • Authors and year deprecated in LICENSE.txt TRIQS/ctseg#14
  • COPYING.txt TRIQS/ctseg#11
• Contribution and authorship: Has the submitting author (@nkavokine) made major contributions to the software? Does the full list of paper authors seem appropriate and complete?
• Substantial scholarly effort: Does this submission meet the scope eligibility described in the JOSS guidelines
• Data sharing: If the paper contains original data, data are accessible to the reviewers. If the paper contains no original data, please check this item.
• Reproducibility: If the paper contains original results, results are entirely reproducible by reviewers. If the paper contains no original results, please check this item.
• Human and animal research: If the paper contains original data research on humans subjects or animals, does it comply with JOSS's human participants research policy and/or animal research policy? If the paper contains no such data, please check this item.

Functionality

• Installation: Does installation proceed as outlined in the documentation?
• Functionality: Have the functional claims of the software been confirmed?
• Performance: If there are any performance claims of the software, have they been confirmed? (If there are no claims, please check off this item.)
  • Ergodicity problem c.f. triqs_cthyb (possibly due to lack of segment pair moves) TRIQS/ctseg#19

Documentation

• A statement of need: Do the authors clearly state what problems the software is designed to solve and who the target audience is?
• Installation instructions: Is there a clearly-stated list of dependencies? Ideally these should be handled with an automated package management solution.
• Example usage: Do the authors include examples of how to use the software (ideally to solve real-world analysis problems).
• Functionality documentation: Is the core functionality of the software documented to a satisfactory level (e.g., API method documentation)?
• Automated tests: Are there automated tests or manual steps described so that the functionality of the software can be verified?
  • Test dimer.py does not test anything TRIQS/ctseg#15
  • Missing tests for correctness? TRIQS/ctseg#16
• Community guidelines: Are there clear guidelines for third parties wishing to 1. Contribute to the software 2. Report issues or problems with the software 3. Seek support

Software paper

• Summary: Has a clear description of the high-level functionality and purpose of the software for a diverse, non-specialist audience been provided?
• A statement of need: Does the paper have a section titled 'Statement of need' that clearly states what problems the software is designed to solve, who the target audience is, and its relation to other work?
• State of the field: Do the authors describe how this software compares to other commonly-used packages?
• Quality of writing: Is the paper well written (i.e., it does not require editing for structure, language, or writing quality)?
• References: Is the list of references complete, and is everything cited appropriately that should be cited (e.g., papers, datasets, software)? Do references in the text use the proper citation syntax?
  • [doc] add refs to about TRIQS/ctseg#18

[nkavokine]

@egcpvanloon @HugoStrand thank you for going through the code and for making very pertinent remarks. I believe I have now addressed all of them. Is there anything else that we should address?

[lucydot]

Hello @egcpvanloon @HugoStrand - how are your reviews going?

It seems there has been some nice work done on this review, but still some outstanding boxes yet to be ticked. Please could you indicate which ones are now addressed, and let @nkavokine know if there is more action to take. Thank-you - Lucy.

[lucydot]

A note here that I am going to take two weeks leave, and will be back on the 6th of Jan.

[egcpvanloon]

In the group, we've been using ctseg the last few months and have tested functionality and performance, mostly in the context of single-orbital impurity models with retarded interactions. Installation and usage are straightforward and the code performs well. I have completed the checklist above (incl. some comments) and support publication in JOSS.

[HugoStrand]

Dear @nkavokine and @lucydot,

I have two open concerns regarding

• the testing and benchmarking for functionality/correctnes, and
• ergodicity problems absent in the triqs_cthyb implementation of the CTHYB algorithm.

@nkavokine I understand that it might not be possible to test for correctness in the automated tests. However, as you point out (TRIQS/ctseg#15 and TRIQS/ctseg#16) there are examples in the test suite that could be used to check correctness but only if substantial computational resources were used. In triqs_cthyb this has been handled by lifting out these cases into a separate set of manual benchmarks, not part of the automated test suite, that is used to test for correctness in harder and more computationally demanding (corner) cases, see https://github.com/TRIQS/cthyb/tree/3.3.x/benchmark . It would be great if you could do the same in triqs_ctseg in particular for the comparison with the ctint code.

Regarding the ergodicity problem TRIQS/ctseg#19, I find it surprising that triqs_cthyb is able to do "better" than triqs_ctseg. However, I am not certain that the minimal example captures the full complexity of the ergodicity problems in the multiorbital models. (Ferrero and Parcollet know the details.) Perhaps this case is due to the choice of an empty configuration as starting configuration. This particular single band case could probably be solved with a segment inversion move. However, that would not solve the issue in multiband models.

Best regards,
Hugo

[lucydot]

Thank you @egcpvanloon and @HugoStrand for your work and insights. @nkavokine it is over to you and your team to address the points raised by @HugoStrand. Please let me know if I can clarify anything as editor.