Hi Saswata, 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.
-Paul Grant W2AGZ Technologies. -----Original Message----- From: pw_forum-boun...@pwscf.org [mailto:pw_forum-boun...@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. Dear All, 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). &CONTROL calculation='vc-relax', restart_mode='from_scratch', prefix='BST' pseudo_dir = '/home/saswata/espresso/potentials/', outdir='./' tstress=.true. tprnfor=.true. verbosity='high' wf_collect=.true. nstep=200 etot_conv_thr=1.0D-7 forc_conv_thr=1.0D-4 disk_io='default' / &SYSTEM ibrav = 2, celldm(1) =16.0208, nat = 10, ntyp= 4, ecutwfc = 80.0, ecutrho=800, occupations='smearing', smearing='gaussian', degauss=0.02, nspin=2, starting_magnetization(2)=0.4, lda_plus_u=.true., Hubbard_U(2)=7.0, / &ELECTRONS diagonalization='david', mixing_mode='plain', mixing_beta = 0.7D0 conv_thr = 1.0D-9 electron_maxstep=200 / &IONS ion_dynamics='bfgs' upscale=10D0 trust_radius_max=1.0D0 trust_radius_min=1.0D-5 trust_radius_ini=0.5D0 w_1=0.01D0 w_2=0.5D0 / &CELL cell_dynamics='bfgs', press=0.0, cell_factor=2.5D0, press_conv_thr=0.2, / ATOMIC_SPECIES 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 ATOMIC_POSITIONS crystal 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 K_POINTS automatic 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, Saswata Halder. Senior Research Fellow Bose Institute. _______________________________________________ Pw_forum mailing list Pw_forum@pwscf.org http://pwscf.org/mailman/listinfo/pw_forum
