The LDA gap here is around 80meV. The experimental gap is around 150meV. I may have to manually change the dielectric constant to experimental value before feeding it to EPW.
Thanks Paolo, Vahid > On Dec 23, 2025, at 8:09 AM, Paolo Giannozzi <[email protected]> wrote: > > CAUTION: The Sender of this email is not from within Dalhousie. > > Maybe your computed gap is very small (and smaller than the experimental > one)? > > Paolo > > On 12/23/2025 1:03 PM, Vahid Askarpour wrote: >> Dear QE Community, >> >> When doing ph.x calculation on the bulk Bi2Te3 with qe-7.3.1, I get the >> following for the dielectric constant >> >> >> End of electric fields calculation >> Dielectric constant in cartesian axis >> >> ( 492.092803103 0.000000000 -0.000000000 ) >> ( 0.000000000 492.092803103 -0.000000000 ) >> ( 0.000000000 -0.000000000 100.437749350 ) >> >> The preliminary scf calculation was done with the following scf.in >> >> &control >> calculation='scf', >> restart_mode='from_scratch', >> prefix='Bi2Te3', >> pseudo_dir='./' >> verbosity='high', >> tprnfor=.true., >> tstress=.true., >> etot_conv_thr=1.0d-6 >> forc_conv_thr=1.0d-5 >> / >> &system >> ibrav=0, >> nat=5, ntyp= 2, >> ecutwfc = 110, >> occupations='fixed' >> lspinorb= .true. >> noncolin=.true. >> / >> &electrons >> diagonalization='cg' >> conv_thr = 1.0e-10 >> mixing_beta = 0.5 >> electron_maxstep = 500 >> mixing_mode = 'plain' >> / >> ATOMIC_SPECIES >> Bi 208.9804 Bi-d_r.upf >> Te 127.6 Te-d_r.upf >> CELL_PARAMETERS (angstrom) >> 2.19309263036978 -1.26618262050178 10.15655859709168 >> 0.00000000000000 2.53236524100356 10.15655859709168 >> -2.19309263036978 -1.26618262050178 10.15655859709168 >> ATOMIC_POSITIONS (crystal) >> Bi 0.40035000000000 0.40035000000000 0.40035000000000 >> Bi 0.59965000000000 0.59965000000000 0.59965000000000 >> Te 0.20882000000000 0.20882000000000 0.20882000000000 >> Te 0.79118000000000 0.79118000000000 0.79118000000000 >> Te 0.00000000000000 0.00000000000000 0.00000000000000 >> >> K_POINTS (automatic) >> 12 12 12 0 0 0 >> >> I expected dielectric constants around 50. I am not sure if I am making a >> mistake or if this is a bug. Any suggestion is appreciated. >> >> Thanks, >> >> Vahid >> >> Vahid Askarpour >> Department of Physics and Atmospheric Science >> Dalhousie University >> Halifax, Canada >> >> >> _______________________________________________________________________________ >> The Quantum ESPRESSO Foundation stands in solidarity with all civilians >> worldwide who are victims of terrorism, military aggression, and >> indiscriminate warfare. >> -------------------------------------------------------------------------------- >> Quantum ESPRESSO is supported by MaX (www.max-centre.eu) >> users mailing list [email protected] >> https://lists.quantum-espresso.org/mailman/listinfo/users > > -- > Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche, > Univ. Udine, via delle Scienze 206, 33100 Udine Italy, +39-0432-558216 > _______________________________________________________________________________ The Quantum ESPRESSO Foundation stands in solidarity with all civilians worldwide who are victims of terrorism, military aggression, and indiscriminate warfare. -------------------------------------------------------------------------------- Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list [email protected] https://lists.quantum-espresso.org/mailman/listinfo/users
