question about ypp -e a

[amolina]

Dear users and developers,

I have a question of how to interpret the output given by the postprocessing tool "ypp -e a". In my particular case, for the system hexagonal boron nitride, where the excitons comes from the top valence band and the bottom conduction band, I get the following output:

# __ __ _ __ __ ____ U ___ u
# \ \ / / U /"\ U u |" \/ "| u U | __") u \/"_ \/
# \ V / \/ _ \/ \| |\/| |/ \| _ \/ | | | |
# U_|"|_u / ___ \ | | | | | |_) | .-,_| |_| |
# |_| /_/ \_\ |_| |_| |____/ \_)-\___/
# .-,//|(_ \\ >> <<,-,,-. _|| \\_ \\
# \_) (__) (__) (__) (./ \.) (__) (__) (__)
#
# GPL Version 3.2.4 Revision 855
# http://www.yambo-code.org
#
# BSK|Identifier :8481
# |Dimension :576
# |Bands :4 - 5
# |Exchange [res]: yes
# |Correlation [res]: yes
# |Kernel`s coupling : no
# |Exchange [cpl]: no
# |W interaction is bare : no
# |Correlation [cpl]: no
# |ALDA kernel in R-space : no
# |RL vectors [exchange]:4441
# |RL vectors [correlation]:111
# |E/h energy range [ev]:-1.000000 - -1.000000
# |Coupling range [o/o]: 100.0000 - 100.0000
# W |Interaction is diagonal : no
# |Matrix size :111
# |Bands :1 - 100
# |e/h energy range [ev]:-1.000000 - -1.000000
# |Poles [o/o]: 100.0000
# |Rl vectors in the sum :4441
# |[r,Vnl] included : yes
# |Field direction :0.1000E-4 0.000000 0.000000
# |Coulomb Cutoff :none
# |xc-Kernel :none
# RIM|RL components [col]:0
# |Random points [col]:0
#
# Electron-Hole pairs that contributes to Excitonic State 1 more than 5%
#
# K-point [iku] Weight
# 0.45833 0.27083 0.00000 0.05381
# 0.41667 0.33333 0.00000 0.09777
# 0.375000 0.354167 0.000000 0.110875
# 0.41667 0.37500 0.00000 0.09128
# 0.333333 0.375000 0.000000 0.116785
# 0.375000 0.395833 0.000000 0.289227
# 0.291667 0.395833 0.000000 0.118626
# 0.333333 0.416667 0.000000 0.379334
# 0.375000 0.437500 0.000000 0.318218
# 0.291667 0.437500 0.000000 0.207258
# 0.333333 0.458333 0.000000 1.000000
# 0.333333 0.500000 0.000000 0.246947
#
# Band_V Band_C K ibz Symm. Weight Energy
#
4.00000 5.00000 61.00000 1.00000 0.07295 4.58724
4.00000 5.00000 61.00000 2.00000 0.07295 4.58724
#
# YPP@vargas003 x 001 CPUs * 05/15/2012 14:01 [start]
# 05/15/2012 14:01 [end]
#
# Cpu Timing [Min/Max/Average]: 01s/01s/01s
#
# .-Input file : ypp.in
# | excitons # [R] Excitons
# | amplitude # [R] Amplitude
# | States= "1 - 10" # Index of the BS state(s)
# | Degen_Step= 0.0100 eV # Maximum energy separation of two degenerate states



Why is there a list of K-points and weights commented before the list of band_V and band_C?

Why is there not correspondence between both list in terms of numbers of K-points?


Thanks for your help,

Alejandro.

[Daniele Varsano]

Dear Alejandro,
in the amplitude output first the total weight vs K-points are summarized,
next the detailed list of transitions and energy difference are reported.
Please note that only the transition that contributes more than 5% are reported.
Cheers,

Daniele

[andrea marini]

in the amplitude output first the total weight vs K-points are summarized

Let me be more specific in case the answer of Daniele is not clear enough. An excitonic state is a sum of e/h pairs. Each labelled with k-point, valence and conduction band indexes. The numbers reported at the beginning are the sums of the contributions coming from ALL the e/h pairs labelled with a specific k-point.

Is it clear, now Alejandro ?

Andrea

[amolina]

Thanks Danielle and Andrea for the answer, now it is clear. But I have still a doubt... Why if in the first list I have a non-negligible weight for a k-point, let's say 0.3333 0.50000, this point it is not in the second list? It is because the contribution of a single pair (e,h,k) is smaller than 5 %?

Cheers,

Alejandro.

[Daniele Varsano]

Dear Alejandro,

It is because the contribution of a single pair (e,h,k) is smaller than 5 %?

yes, it's like you argued.

Best,

Daniele