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Ameland

Member

From: Uni Bonn

Registered: 2026-02-14

Posts: 4

Question about NICS calculations using ORCA

I would like to ask whether it is possible to calculate the NICS values presented in Figure 5 and Table 5 of your paper (DOI: 10.1002/chem.202403369) using ORCA.

Thank you for your time and help.

sobereva

Tian Lu (Multiwfn developer)

From: Athens, Greece

Registered: 2017-09-11

Posts: 2,304

Website

Re: Question about NICS calculations using ORCA

They are realized via Multiwfn, unfortunately, this function is currently not possible for ORCA users. Please check this post for reason: http://sobereva.com/wfnbbs/viewtopic.php?id=1847

saeed_E

Member

Registered: 2019-12-21

Posts: 356

Re: Question about NICS calculations using ORCA

Dear Tian,

I hope this message finds you in excellent health and spirits.

As I regularly visit the Multiwfn homepage and check its forum, I happened to come across this post quite by chance.

Some time ago, I prepared a detailed tutorial explaining how to perform a scan with ORCA 6.1.1 to calculate NICS\(_{zz}\) values above a planar aromatic ring. I also included a simple Python script designed to be run once the ORCA calculations are complete. The user simply needs to provide the full path to the ORCA output (.log) file. The script automatically reads the log file, extracts all the NICS\(_{zz}\) values, saves the results in a text file, and generates a two-dimensional plot of NICS\(_{zz}\) as a function of the distance from the ring center, identifying and reporting both the position and the value of the minimum.

The ORCA input file, named NICS_SCAN.inp, can serve as a reusable template for future calculations. The user only needs to insert the fully optimized Cartesian coordinates of the system of interest and appropriately adjust the scan parameters.

A comprehensive, step-by-step manual is also provided in the Manual subfolder.

I would be truly delighted if you could review these materials and confirm their scientific accuracy and methodological validity. Your expert opinion would be greatly appreciated, as it would help ensure that the person who kindly shared this post, along with other members of the community, can confidently benefit from these files.

Thank you very much for your time and consideration.

With my warmest regards and deepest respect,
Saeed

NICS_extractor(ORCA6.1.1)-and_plotter.zip

saeed_E

Member

Registered: 2019-12-21

Posts: 356

Re: Question about NICS calculations using ORCA

Dear friends,

Since this topic seems to have attracted some interest, please allow me to share the following additional information regarding the basis set employed in NMR calculations:
For the calculation of nuclear magnetic shielding tensors, the pcSseg-3 basis set was employed. This choice is consistent with the recommendations provided in the ORCA 6.1.1 manual, which advocates the use of basis sets incorporating tight Gaussian exponents, such as the purpose-designed pcSseg-n family, for NMR calculations. These property-optimized basis sets are specifically tailored to improve the description of nuclear magnetic shielding constants. The suitability of pcSseg-3 is further illustrated by its explicit use in the official ORCA NMR tutorial for shielding calculations. Furthermore, this basis set is available for elements up to krypton (Kr), thereby encompassing selenium.

Refs:
Jensen, F. Segmented Contracted Basis Sets Optimized for Nuclear Magnetic Shielding. Journal of Chemical Theory and Computation 2015, 11 (1), 132–138. DOI: 10.1021/ct5009526
ORCA 6.1.1 Manual, Sections 2.7 and 5.21.1–5.21.3].

sobereva

Tian Lu (Multiwfn developer)

From: Athens, Greece

Registered: 2017-09-11

Posts: 2,304

Website

Re: Question about NICS calculations using ORCA

pcSseg-3 is fairly accurate for NMR. However its advantage compared to the much cheaper pcSseg-2 is not very obvious. So I would like to mention when pcSseg-3 is too expensive to use, pcSseg-2 is a very good alternative.

saeed_E

Member

Registered: 2019-12-21

Posts: 356

Re: Question about NICS calculations using ORCA

Dear Tian,
Your very valuable and informative comment is deeply appreciated.
Would it be possible for the Python code that has been developed to be incorporated as a module into a future release of Multiwfn, so that NICS calculations could be carried out conveniently and automatically within Multiwfn?

Sincerely,
Saeed

sobereva

Tian Lu (Multiwfn developer)

From: Athens, Greece

Registered: 2017-09-11

Posts: 2,304

Website

Re: Question about NICS calculations using ORCA

As I noted in #2, the support for NICS/ICSS calculation of ORCA in Multiwfn will be considered when the need of basis function at the target position is removed....

saeed_E

Member

Registered: 2019-12-21

Posts: 356

Re: Question about NICS calculations using ORCA

My very dear friend, Tian,

I am infinitely grateful for your detailed explanations and comments. However, it appears that the template I wrote has solved this problem, and this template can be used as a standard template for all NICS-type calculations and the scan in question. The user only needs to correctly enter the geometric specifications of their desired compound and the coordinates of the ring center for X and Y. Of course, I may be mistaken and may not have properly evaluated all aspects of the work and calculations. If that is the case, and if my view has a scientific flaw, please guide me as always with your highly valuable and precise comments.

With utmost respect and devotion,
Saeed