Yambo Community Forum

Dear all,
I ran a BSE calculation of bulk BN on Yambo and tried to use ypp to get weights. But I didn't get the band information about the exciton. I wonder if I made a mistake in the input of ypp. The input and output are as follows. Any suggestions would be very valuable to me.
# .-Input file : ypp_ampl.in
# | excitons # [R] Excitons
# | amplitude # [R] Amplitude
# | BoseTemp= 0.000000 eV # Bosonic Temperature
# | States= "3 - 4" # Index of the BS state(s)
# | Qpts= 1 # Index q of the BS state(s)
# | DipWeight # Weight the contribution to the exciton WFs with the dipoles
# | Degen_Step= 0.0100 eV # Maximum energy separation of two degenerate states

# Electron-Hole pairs that contributes to Excitonic State 3 for iq=1 more than 5.000000%
#
# K-point [iku] Weight
# 0.05556 0.47222 0.16667 0.05016
# 0.11111 0.50000 0.16667 0.06643
# 0.166667 0.472222 0.000000 0.124443
# 0.166667 0.472222 0.166667 0.215430
# 0.166667 0.472222 0.333333 0.158887
# 0.16667 0.47222 -0.50000 0.06910
# 0.222222 0.444444 0.000000 0.118933
# 0.222222 0.444444 0.166667 0.219726
# 0.222222 0.444444 0.333333 0.179064
# 0.22222 0.44444 -0.50000 0.07937
# 0.222222 0.500000 0.000000 0.161004
# 0.222222 0.500000 0.166667 0.309042
# 0.222222 0.500000 0.333333 0.266194
# 0.222222 0.500000 -0.500000 0.121001
# 0.27778 0.41667 0.00000 0.05546
# 0.277778 0.416667 0.166667 0.105267
# 0.27778 0.41667 0.33333 0.09008
# 0.277778 0.472222 0.000000 0.412778
# 0.277778 0.472222 0.166667 0.895738
# 0.277778 0.472222 0.333333 1.000000
# 0.277778 0.472222 -0.500000 0.510920
# 0.33333 0.50000 0.00000 0.08694
# 0.333333 0.500000 0.166667 0.216113
# 0.333333 0.500000 0.333333 0.352550
# 0.333333 0.500000 -0.500000 0.233160
#
# Band_V Band_C Kv-q ibz Symm_kv Kc ibz Symm_kc Weight Energy
#
#
Thanks in advance.
Huaiyuan

Dear Huaiyuan,
most probably because the weights are small and by default, yambo reports weight that are larger than 5% of the maximum weights.
You can change the default by adding in input the variable "Weight_treshold", (it appears adding -V all when creating the input file) e.g.
Weight_treshold=0.01 (for weight larger than 1%), or set it to 0, to have all the transitions.

Best,
Daniele

Dear Daniele:
Thanks for your helpful reply.
Best,
Huaiyuan