notes for authors

1. Scientific scope

Section A of Acta Crystallographica publishes articles reporting advances in the practice and theory of all areas of structural science in the broadest sense. As well as traditional crystallography, this includes nanocrystals, metacrystals, amorphous materials and quasicrystals. It also covers electron crystallography, diffuse scattering, pair distribution function studies, time-resolved XFEL studies, cryo-EM, tomography, small-angle scattering, coherent scattering, diffraction imaging, and the structure of strain and defects in materials. Contributions on advances in analysis tools that are foundational to crystallography, including descriptions and applications of methods, algorithms and software, and the use of emerging computational approaches such as artificial intelligence and machine learning as applied to structural science, are also welcome.

The central themes of the journal are studies of the properties and arrangements of atoms, ions and molecules in condensed matter, and the experimental, computational and theoretical methods that form the basis for such studies. Priority is given to articles that clearly describe the significance of the work to as wide a structural science readership as possible.

2. Categories of contributions

The journal comprises two sections: Advances and Foundations.

Articles that are likely to be of high impact and broad interest will be considered for the Advances section of the journal. They will benefit from rapid publication (normally 6–8 weeks from submission) and may be accompanied by a Scientific Commentary (see Section 2.7[link]) written for a scientifically literate audience and a press release upon publication. Authors may request that their article is considered for the Advances section when they submit their article (see https://journals.iucr.org/a/services/submit.html for more details).

Contributions should conform to the general editorial style of the journal. Typical articles may be viewed by going to https://journals.iucr.org/a/issues/sample/. Articles should be written with a wide scientific audience in mind.

2.1. Research Papers

Full-length Research Papers should not normally exceed 15 journal pages (about 15 000 words).

2.2. Short Communications

Short Communications are intended for the presentation of topics of limited scope or for preliminary announcements of novel research findings. They are not intended for interim reports of work in progress, and should report results that are of scientific value in their own right.

Short Communications should not normally exceed two journal pages (about 1500 words).

2.3. Lead Articles

Lead Articles are authoritative, comprehensive and forward-looking reviews of major areas of research interest. Suggestions for suitable topics and of potential author(s) are welcomed by the Section Editors.

The Section Editors will discuss the treatment of the topic, and the length and the delivery date of the article with potential author(s).

2.4. Feature Articles

Feature Articles are focused surveys covering recent advances in an area of current research. They should not aim to be comprehensive, but a brief introduction should provide historical perspective and a brief conclusion should indicate likely future directions. Inclusion of new results is appropriate.

Feature Articles will generally be about ten journal pages (10 000 words). Shorter articles on rapidly evolving areas are also actively encouraged.

2.5. Topical Reviews

Topical Reviews aim to capture the current trend of a field and are expected to be relatively short. Typically they should contain about 6000 words and a maximum of 50 references, with half of those having been published in the last three years. Inclusion of new results, as well as a historical perspective, is appropriate.

2.6. Letters to the Editor

These may deal with non-technical aspects of crystallography, its role, its propagation, the proper function of its Societies etc., or may make a technical observation or scientific comment that would usefully be brought to a wider audience. They can also be used as a means of post-publication discussion. Letters should be submitted to the Section Editors.

2.7. Scientific Commentaries

Scientific Commentaries discuss articles of particular importance for the readership of the journal. Suggestions for suitable topics and of potential author(s) are welcomed by the Section Editors.

3. Submission and handling of articles

3.1. Submission

All submissions should be accompanied by a covering letter that explains the significance of the work reported.

Articles should be submitted at https://journals.iucr.org/a/services/submit.html. Full instructions for submitting an article and details of the files required are given at https://journals.iucr.org/a/services/submitinstructions.html. Authors are encouraged to use the templates available from https://journals.iucr.org/a/services/helpsubmit.html. If the article reports a crystal structure, a CIF should be supplied (https://journals.iucr.org/a/services/cifinfo.html).

A single author (the submitting author) should handle the submission of the article and be the contact for any editorial questions during the review and publication processes. The submitting author should provide an e-mail address. The published article may have one or more authors (correspondence authors) who are responsible for communications after publication and are marked with an asterisk in the published article. All authors are strongly encouraged to provide an ORCiD iD during submission.

During submission authors will be encouraged to provide a tweet about their article for use on publication; twitter handles for departments, institutions etc. will also be requested.

3.2. File format

The source files required for an article include: a single file in Word, OpenDocument or LaTeX format of the text, tables and figures of the article; and a high-resolution graphics file (minimum 600 d.p.i.) in TIFF, PostScript, encapsulated PostScript, JPEG or PNG format for each figure and scheme. Supporting information should be provided in one of the formats listed at https://journals.iucr.org/services/filetypes.html. Files should be uploaded as described in the online submission instructions.

3.3. Handling of articles

Advances articles will be seen by the Section Editors before peer review.

Each article is handled by an editor chosen by the author from a list of those available at the time of submission. Authors should choose an editor whose area of expertise most closely matches the subject of the article. Details of the current Editorial Board can be found at https://journals.iucr.org/a/services/editors.html.

All contributions will be seen by referees (normally two) before they can be accepted for publication. The editor to whom the article is assigned is responsible for choosing referees and for accepting or rejecting the article. This responsibility includes decisions on the final form of the article and interpretation of these Notes when necessary. The Co-editor may request revisions to the article (e.g. to the title and abstract) before peer review. Further information on the peer-review process can be found at https://journals.iucr.org/a/services/peerreview.html.

Changes to an article requested by the Section Editors, Co-editor or the editorial staff should be received within two months of transmittal to the author, otherwise the submission will be considered as withdrawn. If an article is not acceptable after two revisions it will not be considered further. Any subsequent communication of the material will be treated as a new submission in the editorial process. An article that has been rejected should not be resubmitted to any IUCr journal unless the reasons given for the rejection have been fully addressed in the revised version.

After initial submission, any revised or new files should be uploaded at the web address provided only in response to a specific request from an editor.

For accepted articles, it is the responsibility of the Managing Editor to prepare the article for publication. This may involve correspondence with the authors and/or the responsible editor in order to resolve ambiguities or to obtain satisfactory figures or tables. The date of acceptance that will appear on the published article is the date on which the Managing Editor receives the last item required. Contact details for the Managing Editor of Section A can be found at https://journals.iucr.org/services/contactus.html.

Articles may be checked for plagiarism using the Crossref Similarity Check service.

3.4. Transfer of articles

On rare occasions, editors may suggest the transfer of an article to another IUCr Journal, if the article appears to be more suited to the other journal. The transfer process is rapid, as articles can be seamlessly transferred from one journal to another together with the corresponding reviews. The editor of the new journal will often make a decision based on the existing reviews, but will sometimes invite additional reviewers. Note that any change to the journal of publication will only be made after full discussion with the submitting author.

3.5. Author's warranty and ethical considerations

The submission of an article is taken as an implicit guarantee that the work is original, that it is the author(s) own work, that all authors are aware of and concur with the submission, that all workers involved in the study are listed as authors or given proper credit in the acknowledgements, that the article has not already been published (in any language or medium), and that it is not being considered and will not be offered elsewhere while under consideration for Acta Crystallographica Section A. Authors should avoid multiple or redundant publication (where essentially the same research is published in more than one journal). The prior inclusion of material in an informal publication, e.g. a preprint server, is welcomed by IUCr Journals.

The co-authors of an article should be all those persons who have made significant scientific contributions to the work reported, including the ideas and their execution, and who share responsibility and accountability for the results. Other contributions should be indicated in the acknowledgements. Changes to the list of authors will normally require the agreement of the editor and all authors.

The IUCr is a member of the Committee on Publication Ethics (COPE) and endorses its recommendations, including the Code of Conduct for Editors, which are available at https://www.publicationethics.org/. For more information about the ethical considerations related to publication, see the IUCr's ethical publishing policy.

Authors publishing in the journal may be asked to review articles submitted to the journal.

3.6. AI tools

Authors may make use of AI tools in preparing their articles. However, such tools may not be listed as an author, as they cannot be held accountable for the work. All co-authors of the text should carefully check for any errors introduced through the use of an AI tool. Authors who have employed an AI tool should document this use in the methods or acknowledgements sections.

3.7. Author grievance procedure

An author who believes that an article has been unjustifiably treated by the Co-editor may appeal initially to the Section Editors for a new review and, finally, to the Editor-in-chief of IUCr Journals if still aggrieved by the decision. The initial appeal should be made within three months of rejection of the article. The decision of the Editor-in-chief is final.

3.8. Licencing

Except as required otherwise by national laws, an author will be required to agree to either a licence to publish or an open-access licence (see Section 3.9[link]) before a manuscript can be accepted. Details of author rights can be found at https://journals.iucr.org/services/authorrights.html.

3.9. Open access

Authors are given the opportunity to make their articles `open access'. Authors of open-access articles will not be asked to transfer copyright to the IUCr, but will instead be asked to agree to an open-access licence. This licence is identical to the Creative Commons Attribution (CC-BY) Licence. Further details can be found at https://journals.iucr.org/a/services/openaccess.html.

3.10. Publication fees

There are no fees for colour figures or electronic reprints. If authors require open access there is a charge and for some authors this may be covered by a transformative deal with their institution. Full details will be given at the proof stage or see https://journals.iucr.org/a/services/openaccess.html.

4. Article preparation

4.1. General information

Articles should be clearly and simply written so that they are accessible to as broad a readership as possible. Before preparing articles, authors should consult a recent issue of the journal to make themselves familiar with the general format, such as the use of headings, layout of tables and citation of references. A sample issue is available at https://journals.iucr.org/a/issues/sample/.

The title of the article should be written to appeal to a wide audience and should include key phrases in the subject area. The most effective titles are generally no more than 10–12 words in length. The use of acronyms or abbreviations should be avoided.

All contributions should be accompanied by an English language Abstract, and a one- or two-sentence Synopsis of the main findings of the article for inclusion in the contents pages. Authors should also supply at least five keywords. These may include synonyms and specific phrases related to the subject of the article.

The Abstract should state as specifically and as quantitatively as possible the principal results obtained, and should provide an indication of the broader significance of the work. For Research Papers, Lead Articles or Feature Articles the Abstract should be around 250 words. For shorter contributions 150 words should suffice. The Abstract should be suitable for reproduction by abstracting services without a change in wording. It should make no reference to tables, diagrams, atom numbers or formulae contained in the article. It should not contain footnotes and should not include the use of `we' or `I'.

4.2. Quality of writing

Articles should be clearly written and grammatically correct. If the Co-editor concludes that language problems would place an undue burden on the referees, the article may be returned to the authors without review. Details of language-editing services can be found at https://journals.iucr.org/services/languageservices.html.

4.3. Diagrams and photographs (`figures')

A set of guidelines for preparing figures is available from https://journals.iucr.org/a/services/help/artwork/guide.html. Figures should be prepared using one of the file formats listed in Section 3.2[link].

The choice of figures should be optimized to produce the shortest article consistent with clarity. Duplicate presentation of the same information in both figures and tables is to be avoided, as is redundancy with the text. Supplementary figures may be deposited (see Section 6[link]).

An image should be provided which summarizes the message of the paper, and can be used as a graphical abstract or thumbnail on the contents pages and the first page of the article.

In articles which use powder-profile fitting or refinement (Rietveld) methods, figures that present the experimental and calculated diffraction profiles of the material studied should also contain the difference profile. As primary diffraction data cannot be satisfactorily extracted from such figures, the basic digital diffraction data should be deposited (see Section 5[link]).

4.3.1. Quality

Electronic files in the formats listed in Section 3.2[link] are essential for high-quality reproduction. The resolution of bitmap graphics should be a minimum of 600 d.p.i.

4.3.2. Size

Diagrams should be as small as possible consistent with legibility. They will normally be sized so that the greatest width including lettering is less than the width of a column in the journal (8.8 cm).

4.3.3. Lettering and symbols

Fine-scale details and lettering should be large enough to be clearly legible (ideally 1.5–3 mm in height) after the whole diagram has been reduced to one column width.

Lettering should be kept to a minimum; grids and shadings should be avoided where they are not required for clarity. Descriptive matter should be placed in the caption.

4.3.4. Numbering and captions

Diagrams should be numbered in a single series in the order in which they are referred to in the text. A list of figure captions should be included in the article.

4.3.5. Colour figures

Colour figures are accepted at no cost to the author.

Authors preparing colour figures should consider how the figure would look if printed in greyscale and to readers who are colour-blind. It is very important that poor contrast (e.g. pale colours with a white background) be avoided.

4.3.6. Cover figure

Authors are encouraged to supply suggestions for the cover illustration of the journal.

4.4. Tables

Authors submitting in Word should use the Word table editor to prepare tables.

4.4.1. Use of tables

Extensive numerical information is generally most economically presented in tables. Text and diagrams should not be redundant with the tables.

Structure factors, anisotropic displacement parameters, least-squares planes and unrefined H-atom coordinates are usually deposited as electronic files, see Section 5[link].

4.4.2. Design, numbering and size

Tables should be numbered in a single series of arabic numerals in the order in which they are referred to in the text. They should be provided with a caption.

Tables should be carefully designed to occupy a minimum of space consistent with clarity.

4.5. Video and multimedia content

Multimedia content (e.g. time-lapse sequences, three-dimensional structures) is welcomed. The preferred file formats for multimedia are given at https://journals.iucr.org/services/filetypes.html.

4.6. Mathematics and letter symbols

Authors submitting in Word should use the Word equation editor to prepare displayed mathematical equations.

The use of the stop (period) to denote multiplication should be avoided except in scalar products. Generally, no sign is required but, when one is, a multiplication sign (×) should be used.

Scalar variables and non-standard functions should appear in italic type.

Vectors should be in bold type and tensors should be in bold-italic type.

Greek letters should not be spelled out.

Care should be taken not to cause confusion by using the same letter symbol in two different meanings.

Gothic, script or other unusual lettering should be avoided. Another typeface may be substituted if that used by the author is not readily available.

All displayed equations, including those in published Appendices, should be numbered in a single series.

4.7. Nomenclature

4.7.1. Units

The International System of Units (SI) is used except that the ångström (symbol Å, defined as 10−10 m) is generally preferred to the nanometre (nm) or picometre (pm) as the appropriate unit of length. Recommended prefixes of decimal multiples should be used rather than `× 10n'.

4.7.2. Crystallographic nomenclature

Authors should follow the general recommendations produced by the IUCr Commission on Crystallographic Nomenclature (see reports at https://www.iucr.org/resources/commissions/crystallographic-nomenclature/).

Atoms of the same chemical species within an asymmetric unit should be distinguished by an appended arabic numeral. Chemical and crystallographic numbering should be in agreement wherever possible. When it is necessary to distinguish crystallographically equivalent atoms in different asymmetric units, the distinction should be made by lower-case roman numeral superscripts (i.e. i, ii, iii etc.) to the original atom labels.

Space groups should be designated by the Hermann–Mauguin symbols. Standard cell settings, as listed in Volume A of International Tables for Crystallography, should be used unless objective reasons to the contrary are stated. When a non-standard setting is used, the list of equivalent positions should be given. Hermann–Mauguin symbols should also be used for designating point groups and molecular symmetry. It is helpful if the origin used is stated explicitly where there is a choice.

The choice of axes should normally follow the recommendations of the Commission on Crystallographic Data [Kennard et al. (1967). Acta Cryst. 22, 445–449].

A symbol such as 123 or hkl without brackets is understood to be a reflection, (123) or (hkl) a plane or set of planes, [123] or [uvw] a direction, {hkl} a form and 〈uvw〉 all crystallographically equivalent directions of the type [uvw]. Other bracket notations should be explicitly defined.

If a crystallographic term carries a specific meaning but is already established with a different meaning in another field, it is acceptable to use the term in that manner as long as its intended meaning is evident within the context of the paper.

4.7.3. Nomenclature of chemical compounds etc

Names of chemical compounds and minerals are not always unambiguous. Authors should therefore quote the chemical formulae, including chemical structural diagrams for organic and metal-organic compounds, of the substances dealt with in their articles.

Chemical formulae and nomenclature should conform to the rules of nomenclature established by the International Union of Pure and Applied Chemistry (IUPAC), the International Union of Biochemistry and Molecular Biology (IUBMB), the International Mineralogical Association (IMA) and other appropriate bodies. As far as possible, the crystallographic nomenclature should correspond to the systematic name.

Any accepted trivial or non-systematic name may be retained, but the corresponding systematic (IUPAC) name should also be given.

4.8. Funding information

Articles may include a Funding information section. This section aims to help authors comply with the reporting requirements of funders, and includes information on funders and grant/award numbers. Funding information should not be included in the Acknowledgements section. For more information, see https://journals.iucr.org/services/funding.html.

4.9. References

References to published work should be indicated by giving the authors' names followed immediately by the year of publication, e.g. Neder & Schulz (1998) or (Neder & Schulz, 1998). Where there are three or more authors, the reference in the text should be indicated in the form Smith et al. (1998) or (Smith et al., 1998).

The reference list should be arranged alphabetically and conform with the following style:

Arnal, R. D. & Millane, R. P. (2022). Acta Cryst. A78, 249–261.

Baake, M. & Grimm, U. (2013). Aperiodic Order, Vol. 1, A Mathematical Invitation. Cambridge University Press.

Cowley, J. M. (1993). Editor. Electron Diffraction Techniques. Oxford University Press.

CRC Handbook of Chemistry and Physics (1983). 64th ed., edited by R. C. Weast, p. D-46. Boca Raton: CRC Press.

Damanik, D., Embree, M., Fillman, J. & Mei, M. (2022). arXiv:2209.01443.

Flor, G. de la, Kroumova, E., Hanson, R. M. & Aroyo, M. I. (2023). In preparation.

International Union of Crystallography (2023). (IUCr) International Union of Crystallography, https://www.iucr.org/.

Keller, E. & Pierrard, J.-S. (1999). SCHAKAL99. University of Freiburg, Germany.

Khouchen, M., Klar, P. B, Chintakindi, H., Suresh A. & Palatinus, L. (2023). Acta Cryst. A. In the press.

Knyazev, A., Krupin, A., Gubaidullin, A. & Galyametdinov, Y. (2019). Acta Cryst. B75, https://doi.org/10.1107/S205252061900578X.

Muhammad, W. & Lee, S. H. (2013). PLoS One, 8, e69608.

Say-awen, A. L. D. (2016). PhD thesis, Ateneo de Manila University, Philippines.

Smith, J. M. (2023). Personal communication.

Note that all authors and inclusive page numbers should be given.

Identification of individual structures in the article by use of database reference (identification) codes should be accompanied by a full citation of the original literature in the reference list.

Citations in supporting information should also appear in the main body of the article or be given in a related-literature section.

5. Data requirements

In order that others can reproduce, verify and build on the work published in IUCr Journals, authors are expected to make supporting data freely available. In this context, the IUCr has adopted a data-sharing policy that requires the data supporting the results in a structural article to be peer reviewed and archived either with the IUCr or in an appropriate public repository. For peer-review purposes, authors are asked to provide access to their data on submission.

Although Acta Crystallographica Section A does not normally publish structure determinations, in the case of a structure being published, authors should follow the guidelines for that type of structure.

Authors of articles that report the results of crystal structure determinations of small molecules or materials should supply data as a single electronic file in CIF format. Structure-factor data in CIF format are also required.

For articles that report the results of structure determinations of biological macromolecules, authors should consult the Notes for Authors for Acta Crystallographica Section D for details of data requirements.

Authors of powder diffraction articles should consult the notes provided at https://journals.iucr.org/services/cif/powder.html.

6. Additional supporting information

Additional supporting information (such as experimental analyses, additional figures and multimedia content) that may be of use or interest to some readers but does not form part of the article itself will be made available from the journal website. Arrangements have also been made for such information to be deposited, where appropriate, with relevant databases. In some cases, e.g. large raw data sets, the journal might not host the data but will provide links if DOIs are available for the data.

7. Author information and services

An author services page is available at https://journals.iucr.org/a/services/authorservices.html.

7.1. Author tools

A number of tools are available to help with the preparation of articles.

Word, OpenDocument and LaTeX templates can be downloaded from the author services page.

Table tools within the Word template, the table converter at https://publcif.iucr.org/services/tools or the program publCIF may be used to prepare tables of experimental details and geometric parameters suitable for inclusion in an article.

For structural articles, CIFs can be checked using the checkCIF/PLATON service at https://checkcif.iucr.org and edited using publCIF, available from https://publcif.iucr.org.

7.2. Status information

Authors may obtain information about the current status of their articles at https://journals.iucr.org/services/status.html.

7.3. Proofs

Proofs will be provided in portable document format (pdf). The submitting author will be notified by e-mail when the proofs are ready for downloading.

7.4. Reprints

After publication, the submitting author will be able to download the electronic reprint of the published article, free of charge.

7.5. Open-access articles

The final published version of each open-access article is deposited with PubMed Central on behalf of the authors.

7.6. Publication and social media

Section A is available online at at https://journals.iucr.org/a. Once your article has been published it will also appear on Twitter @ActaCrystA.

7.7. Publicising your article

There are many ways in which the IUCr promotes and raises awareness of articles published in its journals. More information on this and suggestions for how to publicise your articles can be found at https://journals.iucr.org/a/services/articlepublicity.html.

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