Input file generation

In this tutorial you will learn how to generate and modify an input file with Yambo.

Prerequisites

Previous modules

• Initialization for bulk hBN.

You will need:

• The SAVE databases for bulk hBN (Download here)
• The yambo executable

Launch the input file generator

Yambo generates its own input files: you just tell the code what you want to calculate by launching Yambo along with one or more lowercase options. (Uppercase options are considered in the following section).

To see the list of runlevels and options, run yambo -h or better,

$ yambo -H
Tool: yambo 4.1.2 rev.14024
Description: A shiny pot of fun and happiness [C.D.Hogan] 
[Upper case options]
-i		:Initialization
-o <opt>	:Optics [opt=(c)hi is (G)-space / (b)se is (eh)-space ]
-k <opt>	:Kernel [opt=hartree/alda/lrc/hf/sex] 
-y <opt>	:BSE solver [opt=h/d/(p/f)i]  
                (h)aydock/(d)iagonalization/(i)nversion
-r		:Coulomb potential
-x		:Hartree-Fock Self-energy and local XC
-d		:Dynamical Inverse Dielectric Matrix
-b		:Static Inverse Dielectric Matrix
-p <opt>	:GW approximations [opt=(p)PA/(c)HOSEX]
-g <opt>	:Dyson Equation solver
                [opt=(n)ewton/(s)ecant/(g)reen]
-l		:GoWo Quasiparticle lifetimes
-a		:ACFDT Total Energy

Note that multiple options can be used together (in some cases this is actually a necessity). For instance:

yambo -o c -k hartree       Calculate optical spectra including local field effects (Hartree approximation)
yambo -x -g n -p p            Perform a Hartree-Fock and GW calculation using a plasmon-pole approximation

After launching Yambo with a lowercase option, Yambo will generate an appropriate input file (default name: yambo.in) and launch the vi editor. (Editor choice can be changed at configure; alternatively you can use the -Q run time option).

Choosing input parameters

Yambo will also read various parameters from existing database files and/or input files and use them to suggest values or ranges. Let's illustrate this by calculating the static screening for bulk hBN.

cd YAMBO_TUTORIALS/hBN/YAMBO
yambo        (initialize, if you haven't already done so)
yambo -b

and look at the generated input file. Inside you will see a suggested range of bands, which Yambo guesses from the core ns.db1 database.

% BndsRnXd
   1 | 100 |                 # [Xd] Polarization function bands
%

Change these values to 8 | 9 | , save and exit the editor. Now launch the input file generator again:

yambo -b

and notice that your chosen values remain: they are simply read from the yambo.in file. Now run the calculation:

yambo

After a few seconds, the code finishes. If you now look inside the SAVE folder, you will see several new databases:

$ ls SAVE
ns.db1 ns.wf ndb.dip_iR_and_P ndb.em1s ns.gops ns.kindx [...]

Delete the input file yambo.in, and generate the input file for a different task: optical response in the independent particle approximation.

$ rm yambo.in
$ yambo -o c

Looking inside the input file you will find:

% BndsRnXd
 8 |  9 |                   # [Xd] Polarization function bands
%

Here, Yambo has read from the ndb.dip_iR_and_P database and suggests to use the previous values. If at this stage, you decide to change these values (increase the range), Yambo will recompute the relevant database.

Links

• Command line options
• Back to tutorials menu