no -n switch in ypp

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no -n switch in ypp

Post by mcygorek » Thu Feb 08, 2018 5:25 pm


I'm a new user of yambo and I've followed the great tutorial on how to obtain the band structure of hBN.

At some point in the tutorial, it is stated:
Before editing the input file and running the interpolation, it is important to know that ypp uses an algorithm [2] that cannot be used in presence of time-reversal (TR) symmetry. As a first step we therefore remove the TR symmetry by typing:

$ ypp -n

However, In my version of yambo, ypp does not have a "-n" switch.
The output of "ypp -H" is:

___ __ _____ __ __ _____ _____
| Y || _ || Y || _ \ | _ |
| | ||. | ||. ||. | / |. | |
\ _/ |. _ ||.\ / ||. _ \ |. | |
|: | |: | ||: | ||: | \|: | |
|::| |:.|:.||:.|:.||::. /|::. |
`--" `-- --"`-- --"`-----" `-----"

This is ypp 4.2.1 rev.110
Y(ambo) P(ost) P(rocessor)

-h :Short Help
-H :Long Help
-J <opt> :Job string identifier
-V <opt> :Input file verbosity [opt=gen,qp,rt,all]
-F <opt> :Input file
-I <opt> :Core I/O directory
-O <opt> :Additional I/O directory
-C <opt> :Communications I/O directory
-M :Switch-off MPI support (serial run)
-k <opt> :BZ Grid generator [(k)pt,(q)pt,(s)hifted,(h)igh symmetry,(r)andom]
-q <opt> :(g)enerate-modify/(m)erge quasi-particle databases
-w :Wannier 90 interface
-b :Read BXSF output generated by Wannier90
-e <opt> :Excitons [(s)ort,(sp)in,(a)mplitude,(w)ave]
-s <opt> :Electrons [(w)ave,(d)ensity,(m)ag,do(s),(b)ands]
-f :Free hole position [excitons plot]
-m :BZ map fine grid to coarse
-y :Remove symmetries not consistent with an external perturbation
-z :Convert wave--functions to new format

YAMBO developers group (

Has there been a recent change in ypp, or is there a typo in the tutorial?
Is there a more detailed tutorial on how to use ypp?

Moritz Cygorek,
postdoc at University of Ottawa

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Daniele Varsano
Posts: 2315
Joined: Tue Mar 17, 2009 2:23 pm

Re: no -n switch in ypp

Post by Daniele Varsano » Thu Feb 08, 2018 6:30 pm

Dear Moritz,
the correct command line is

Code: Select all

$ypp -y 
remove the comment in the generated file

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and run

Code: Select all


Dr. Daniele Varsano
S3-CNR Institute of Nanoscience and MaX Center, Italy
MaX - Materials design at the Exascale

Posts: 2
Joined: Thu Feb 08, 2018 5:13 pm

Re: no -n switch in ypp

Post by mcygorek » Fri Feb 09, 2018 4:33 pm

Dear Daniele,

thank you very much.
With this, the bandstructure calculation works perfectly.
Maybe it's a good idea to change this in the tutorial,


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