CCSD gradients

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TCE seems to implement CCSD gradients (see test case tce_ccsd_gradient), but this is not mentioned on http://www.nwchem-sw.org/index.php/Capabilities - is this not production ready, or should the capabilities wiki page be updated?

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In the manual of NWChem 6.6, it is indicated that in the TCE module, energy gradient, geometry optimization, and vibrational frequency calculations are supported on the basis of numerical differentiation.
Edited On 6:59:49 PM PDT - Tue, May 31st 2016 by Xiongyan21

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Hrm right - the test case actually runs via finite differences.

I was caught off-guard by the code in src/tce/gradients/tce_gradient.F which calls ccsd_gradient for that case (and that only), so I thought analytical gradients might be implemented.

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in the directory nwchem-6.6/QA/tests/tce_gradients run:
>grep step h2o_ccsd.out

 Finite difference step  1.00000D-02
 step     1 energy         -75.01249910
 step    -1 energy         -75.01184346
 step     2 energy         -75.01160864
 step    -2 energy         -75.01279302
 step     3 energy         -75.01082691
 step    -3 energy         -75.01356776


TCE gradient implemented by numerical differentiation.

Best Vladimir

  • Karol Forum:Admin, Forum:Mod, NWChemDeveloper, bureaucrat, sysop
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The TCE CC gradient implementation has not been released yet. There are still parts of the code that require more extensive testing and verification. Moreover, we really want to improve the scalability of the code. We are planning to have the TCE CC gradients fully implemented by the end of this year.

Best regards,
Karol

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Hi, Karol

can I compile an analytical gradient for testing and how?

Best, Vladimir.

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Hi, all.

How I can set up Finite difference step value? What units is used for it's default value (1.00000D-02)?

Best.

Vladimir.

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This line set stpr_gen:delta 1d-3 just before the task frequency line would give you a step of 1d-3

....

set stpr_gen:delta 1d-3

task  ... frequency
Edited On 10:22:45 AM PST - Wed, Feb 15th 2017 by Edoapra


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