First steps: a walk through from DFT to optical properties

In this tutorial you will learn how to calculate optical spectra using Yambo, starting from a DFT calculation and ending with a look at local field effects in the optical response.

We will use a 3D system (bulk hBN) and a 2D system (hBN sheet).

Before starting, you need to obtain the tarballs for hBN and hBN-2D. See instructions on the main tutorials page.

The steps are the following:

Step 1: DFT calculation of bulk hBN and conversion to Yambo

Follow the DFT and p2y module on bulk hBN and then return to this tutorial "First steps..."

There is no need to complete the module on 2D BN.

Step 2: Initialization of Yambo databases

Use the SAVE folders that are already provided. For the CECAM tutorial, do:

$ cd YAMBO_TUTORIALS/hBN/YAMBO

Now follow the module on Initialization, for both hBN and 2D-hBN, and return to this tutorial "First steps..."

Step 3: Yambo's command line interface

Yambo uses a command line interface to select tasks, generate input files, and control the runtime behaviour.

Command line options are thus divided into uppercase and lowercase options:

• Lowercase: generate input files (and launch the vi editor)
• Uppercase: modify Yambo's default settings, at run time and when generating input files

Lowercase and uppercase options can be used together.

Starting from the hBN/YAMBO folder, follow

1. the module on input file generation (lower case options), and then
2. the module on command line options (upper case options)

and then return to this tutorial "First steps...".

Step 4: Optical absorption in hBN

Follow the module on Optics at the independent particle level for bulk hBN and return to this tutorial "First steps..."

Step 5: Optical absorption in 2D BN

It is now time to complete the module on 2D BN. Follow the DFT and p2y module on 2D hBN, you can repeat all the steps you already did for hBN bulk and then return to this tutorial "First steps..."

Follow the module on Local fields for 2D BN.

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