Dear admin,
I want to ask that when I do a BSE calculation for an AFM system, if I don't set the LTRIPLET = T, all the exciton states I got are singlet only ? Can I obtain the transitions between different spin channels?
Thanks a lot.
LTRIPLET in BSE calculation
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 Global Moderator
 Posts: 8
 Joined: Tue Nov 05, 2019 2:49 pm
Re: LTRIPLET in BSE calculation
Dear user,
If you start from an antiferromagnetic ground state, and perform standard BSE calculations (LHARTREE=.TRUE.; LTRIPLET = .FALSE), you will obtain one set of singlet solutions and one set of triplet solutions. If you set LTRIPLET=.TRUE., which does the same as setting LHARTREE=.FALSE., you will obtain the remaining two sets of triplet solutions, with many (or maybe even all) transition probabilities being zero (i.e. these correspond to dark, potentially long lived triplet excitons).
In order to obtain nonzero transition probabilities for the triplets, you have to perform BSE calculations using LSORBIT = .TRUE. (of course you also need to perform the groundstate calculations using LSORBIT = .TRUE.).
Georg
If you start from an antiferromagnetic ground state, and perform standard BSE calculations (LHARTREE=.TRUE.; LTRIPLET = .FALSE), you will obtain one set of singlet solutions and one set of triplet solutions. If you set LTRIPLET=.TRUE., which does the same as setting LHARTREE=.FALSE., you will obtain the remaining two sets of triplet solutions, with many (or maybe even all) transition probabilities being zero (i.e. these correspond to dark, potentially long lived triplet excitons).
In order to obtain nonzero transition probabilities for the triplets, you have to perform BSE calculations using LSORBIT = .TRUE. (of course you also need to perform the groundstate calculations using LSORBIT = .TRUE.).
Georg

 Global Moderator
 Posts: 42
 Joined: Tue Jan 19, 2021 12:01 am
Re: LTRIPLET in BSE calculation
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