*From*: Marcos Verissimo Alves <marcos_verissimo###id.uff.br>*Subject*: CCL:G: Scientific notation in Gaussian 16*Date*: Tue, 11 Jan 2022 16:59:20 -0300

Hi Andrew,

In Fortran (I'm a Fortran
programmer), we use "D" to designate a double-precision representation
written in scientific notation, while "E" designates simple precision.
That is very likely the reason for the "D" since a quick glance at the Wikipedia page for the list of Quantum Chemistry and
Solid-State Physics software shows that Gaussian is written in
Fortran.

Best
regards,

Marcos

---

Dr. Marcos Verissimo
Alves

Prof. Adjunto II, Curso de Física
Computacional

Instituto de
Ciências Exatas

Universidade Federal
Fluminense

Volta Redonda - RJ,
Brasil

Em ter., 11 de jan. de
2022 às 16:33, Andrew DeYoung andrewdaviddeyoung###gmail.com <owner-chemistry(-)ccl.net> escreveu:

Hi,It appears that various quantities that are output by Gaussian 16 use notation of the form 6.626D-34. Is it correct for me to assume that this represents 6.626*10^(-34), and is equivalent to the scientific notation 6.626E-34 or 6.626e-34 used in other areas, such as in C/C++, Python, and MATLAB? Or does the "D" represent anything different from, or in addition to, "*10^"?Thank you for bearing with me with this question. (I am what we call in the US a millennial, and am not terribly well acquainted with the sometimes historical origins and meanings of notation!)Best,AndrewAndrew DeYoung, PhDDepartment of ChemistryCarnegie Mellon University