[Pw_forum] Application of LDA+U in phonon calculations.
w2agz at w2agz.com
Fri Sep 25 03:52:38 CEST 2015
WRT your question 2, I have posted on the forum for several years pointing out the lack of a tool to calculate e-p interaction in the context of LDA+U. Such a tool is badly needed within QE and supporting response function packages such as Yambo. I've been told the tool may be available in the ELK package, but have not had the opportunity to check this out yet.
From: pw_forum-bounces at pwscf.org [mailto:pw_forum-bounces at pwscf.org] On Behalf Of saswata halder
Sent: Thursday, September 24, 2015 11:59 AM
To: PWSCF Forum
Subject: [Pw_forum] Application of LDA+U in phonon calculations.
At present I am trying to calculate the phonon modes of double perovskite Ba2SmTaO6 having a cubic Fm3m structure. The detailed input of the vc-relax file is provided below (and also attached alongwith).
pseudo_dir = '/home/saswata/espresso/potentials/',
ibrav = 2, celldm(1) =16.0208, nat = 10, ntyp= 4,
ecutwfc = 80.0, ecutrho=800, occupations='smearing',
smearing='gaussian', degauss=0.02, nspin=2,
mixing_beta = 0.7D0
conv_thr = 1.0D-9
Ba 137.327 Ba.pbe-mt_fhi.UPF
Sm 150.360 Sm.pbe-mt_fhi.UPF
Ta 180.94788 Ta.pbe-mt_fhi.UPF
O 15.9994 O.pbe-mt_fhi.UPF
Ba 0.25 0.25 0.25
Ba 0.75 0.75 0.75
Sm 0.00 0.00 0.00
Ta 0.50 0.50 0.50
O 0.264 0.00 0.00
O 0.736 0.00 0.00
O 0.00 0.264 0.00
O 0.00 0.736 0.00
O 0.00 0.00 0.264
O 0.00 0.00 0.736
4 4 4 1 1 1
I specifically have two questions regarding the output of this calculation
1. The structural relaxation occurs but with a pressure value of P=-13.71. What is the significance of this negative pressure?
2. The phonon calculation terminates with an error message 'LDA+U is not implemented in phonon'. Is there any other way to go about with this calculation in the existing QE versions?
Thanking you in advance and awaiting a reply eagerly,
Senior Research Fellow
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