Spring Nature journal \citep{} does not work as it is expected

Question

Basically, I am trying to write a paper for a Springer journal and I am using their template which you can download here. I am uploading it as a Zip file on Overleaf.

Thanks to this answer, I could manage to produce the citations because the bst files they have are in a bst folder, not in the root folder where .tex main article file exists. So I moved a bst file into the root folder. I could use \cite{...} command where it shows reference with number and square brackets, such as [1].

However, as their documentation claims, unfortunately, \citep{...} option is not working. It still gives me the same output as \cite{...} does. In other words, \citep{...} does not print (Jones et al., 1990).

As this answer points out, I tried to write \documentclass{sn-jnl} without "sn-mathphys" but this time, I get an error, "Package natbib Warning: Author undefined for citation 'bib1' on page 2 on input line 129." whic I do have it!

and I tried many things and could not work it out.

Note that minimal example is already in download file with the bib items.

EDIT:

As a commenter points out, here is Springer Nature latex template preamble:

%%\documentclass[pdflatex,sn-basic]{sn-jnl}% Basic Springer Nature Reference Style/Chemistry Reference Style
%%\documentclass{sn-jnl}
%%\documentclass[sn-basic]{sn-jnl}% Basic Springer Nature Reference Style/Chemistry Reference Style
\documentclass[sn-mathphys]{sn-jnl}% Math and Physical Sciences Reference Style
%%\documentclass[sn-aps]{sn-jnl}% American Physical Society (APS) Reference Style
%%\documentclass[sn-vancouver]{sn-jnl}% Vancouver Reference Style
%%\documentclass[sn-aps]{sn-jnl}% APA Reference Style
%%\documentclass[sn-chicago]{sn-jnl}% Chicago-based Humanities Reference Style
%%\documentclass[sn-standardnature]{sn-jnl}% Standard Nature Portfolio Reference Style
%%\documentclass[default]{sn-jnl}% Default
%%\documentclass[default,iicol]{sn-jnl}% Default with double column layout

Here I need to use \documentclass[sn-mathphys]{sn-jnl} since it is a mathematical paper. Besides, I put sn-mathphys.bst file in root folder, as I mentioned above.

This is the claim what this template does with \citep{...} command but it does not work:

Besides, what \citep does is pretty obvious. I want to have authoryear-style citation.

Answer 1

You seem to be under the impression that \citep will (should?) always produce authoryear-style citation call-outs. This impression is not correct.

Specifically, \citep can generate authoryear-style citation call-outs only if the bibliography style that's in use supports this citation call-out style. Unfortunately for you, sn-mathphys is not one of these bibiography styles.

Consider the following minimalist test document:

\documentclass[sn-mathphys]{sn-jnl} % use natbib package and sn-mathphys bib style
\begin{filecontents}[overwrite]{test.bib}
@misc{a:3001, author="Anne Author", title="Thoughts", year=3001}}
\end{filecontents}
%\setcitestyle{authoryear}

\begin{document}
\citep{a:3001}
\bibliography{test}
\end{document}

Sure enough, it produces a numeric-style citation call-out:

If one were to uncomment the directive \setcitestyle{authoryear}, one gets the following error message:

! Package natbib Error: Bibliography not compatible with author-year citations.

(natbib)                Press <return> to continue in numerical citation style.


See the natbib package documentation for explanation.
Type  H <return>  for immediate help.
 ...                                              
                                                  
l.23 ...mand\NAT@force@numbers{}\NAT@force@numbers

What's the upshot? The sn-mathphys bib style is not capable of generating authoryear-style citation call-outs. That is why both \cite and \citep create numeric-style citation call-outs instead.