How to Use the NOMAD Repository

by Pasquale Pavone, Jungho Shin, & Lorenzo Pardini for exciting carbon

Purpose: In this tutorial, the NOMAD Repository will be introduced. Furthermore, it will be explained how to use it for searching and downloading results of ab-initio calculations.


0. Suggestions for this tutorial

The best and more fruitful way to follow this tutorial is to have two windows open at the same time, one showing the tutorial itself, and the other one showing the NOMAD Repository webpage. In this way, the user will be able to follow the instructions of the tutorial on one page, and jump to the other page to apply them.

1. What is NOMAD?

The Novel Materials Discovery (NOMAD) Project is a European Centre of Excellence which is aimed to developing tools for material science and engineering.

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In particular, the NOMAD Laboratory develops a Materials Encyclopedia, Big-Data Analytics, and Advanced Graphics Tools.

Eight complementary computational materials science groups and four high-performance computing centers form the synergetic core of this Centre of Excellence and participate in the development of the NOMAD Project.

i) The NOMAD Repository

The NOMAD Repository is the part of the NOMAD Project which was established to host, organize, and share materials data. By following the link to the repository webpage, you see the following on the screen.

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In particular, the number 49,238,833 in the right panel indicates the actual number of open-access calculations which are contained in the repository.


2. How to use the NOMAD Repository for searching and downloading results of calculations

In order to proceed with the search, proceed to the NOMAD Repository webpage and click on the SEARCH AND DOWNLOAD button in the horizontal command bar.

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A new page will appear with the search queries.

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i) Your very first search example

As a first example of search we will look for all calculations in the repository which are performed on systems containig both the lithium and fluorine atoms and using the exciting code. In order to do that, start your query by clicking the lithium element (Li) in the periodic table in the section Chemical Elements.

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Wait a few moments which are used by the searching machine of the repository for sorting your query. Then, using the same procedure, add the fluorine element (F).

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Notice that after each choice, the field of remaining elements will be restricted to the ones for which calculations are present in the repository, compatibly with the choices you have already done.

Now, click on the lens symbol in Code of the Methodology section and choose the exciting code.

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You may notice that all your current queries appear in the left top part of the screen.

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Here, if you wish, you can delete one or more topics from the query list. If you want now to procede with the search, push the Search button on the top left margin of the screen.

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After a few moments the results of your search will appear on the screen.

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Two datasets and four calculations appear on the top and bottom panel, respectively. The content of a dataset can be visualized by clicking on the dataset itself. The calculations belonging to that dataset will then appear in the bottom panel. By clicking again on the dataset, we go back to the original result of the search, as in the previous figure. Here, we choose to concentrate on the last item of the calculations panel and we click on the corresponding Show button. A new small window will appear.

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We focus on the first calculation that appear in the Upload date panel. In order to make it appear, we click on it and we get the following:

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Among the indicated files you can select those you want to download by first clicking on the corresponding small icons.

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Finally, for the download, click on the Download selected files button. The selected files will be now in your computer.

Exercises
  • Find all the calculations in the repository performed on systems containing vanadium and oxygen, using GGA as xc functional and numeric AOs as basis set.
  • Find all the open-access calculations in the repository performed on systems containing exclusively sulfur, carbon, and hydrogen, using (L)APW+lo as basis set. Which code was used to perform these calculations? Does the result page show datasets? If yes, what is their content?

3. How to upload your own data


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