A few points about your inputs: 1. You may want to lower both force and energy convergence thresholds by a factor of 10
2. You are using smearing. Is this a metal? If not, try a fixed occupation 3. For a bilayer, the KPOINTS should be like 4 4 1 or 6 6 1. From experience, since your a=3 angstrom, I would start by a K-grid of 1010 1. 4. For phonon calculations, nq3=1. Your nq1 and nq2 are too small. So when interpolating for phonon dispersion calculations, you do not have enough q-points in the BZ to get a nice dispersion. 5. You may like to lower the tr2_ph to 1.0d-16. I have even gone to 1.0d-22 to avoid some negative frequencies. 6. Last but not least, the PSP may be the issue. Cheers, Vahid Vahid Askarpour Department of Physics Dalhousie University Halifax, NS CANADA On Aug 4, 2023, at 8:00 AM, Vahid Askarpour <vh261...@dal.ca> wrote: If the coordinates of the atoms are correct for the bilayer, you just need to add vacuum by adding 15 to 20 Ang to the c value. Cheers, Vahid Vahid Askarpour Department of Physics Dalhousie University Halifax, NS CANADA On Aug 4, 2023, at 7:08 AM, Giuseppe Scala <g.sca...@campus.unimib.it> wrote: CAUTION: The Sender of this email is not from within Dalhousie. The c parameter is set in that way in order to have 10 angstrom vacuum between two sets of Bilayer in my structure. If I reduce the c parameter i think that my system won't be a Bilayer anymore. Is that line of reasoning wrong? Il ven 4 ago 2023, 05:15 ANAND JHA <anandk...@iitk.ac.in<mailto:anandk...@iitk.ac.in>> ha scritto: C parameter and a parameter are wrong they are too high and low On Thu, 3 Aug 2023 at 20:01, Giuseppe Scala <g.sca...@campus.unimib.it<mailto:g.sca...@campus.unimib.it>> wrote: Hi ANAND, Would you mind if I ask you to tell me where's the problem in the structure? Maybe that c parameter is too high or low? Il gio 3 ago 2023, 12:58 ANAND JHA <anandk...@iitk.ac.in<mailto:anandk...@iitk.ac.in>> ha scritto: There is some issue in your bilayer Try to make a new bilayer with CRYSTAL SOFTWARE On Thu, 3 Aug 2023 at 03:55, Giuseppe Scala <g.sca...@campus.unimib.it<mailto:g.sca...@campus.unimib.it>> wrote: I get negative frequencies at gamma points for Bilayer MoS2. I relaxed my structure and checked convergence with respect to energy cutoff. That's my input file for the scf calculation: ############## &CONTROL calculation ='scf' prefix = 'MoS2_BI' pseudo_dir = '/home/Giuseppe' outdir = './' tstress = .true. tprnfor = .true. forc_conv_thr = 1.0d-3 nstep = 200 / &SYSTEM ibrav = 4 a = 3.1429635960300000000 c = 20.006663000000000000 nat = 6 ntyp = 2 ecutwfc = 60 ecutrho = 240 occupations = 'smearing' degauss = 0.01 / &ELECTRONS mixing_beta = 0.7 conv_thr = 1.0d-8 diagonalization = 'david' electron_maxstep=200 / &IONS trust_radius_max = 0.2 / &CELL cell_dynamics = "bfgs" cell_dofree = '2Dxy' / ATOMIC_SPECIES Mo 95.9400 Mo.pbesol-spn-kjpaw_psl.1.0.0.UPF S 32.0660 S.pbesol-n-kjpaw_psl.1.0.0.UPF ATOMIC_POSITIONS {angstrom} Mo 1.5714815237 0.9072955423 6.6890512735 Mo 0.0000000000 1.8145901001 13.377562735 S 1.5714815237 0.9072955423 11.825385701 S 1.5714815237 0.9072955423 14.928508325 S 0.0000000000 1.8145901001 8.2412092563 S 0.0000000000 1.8145901001 5.1381015776 K_POINTS {automatic} 4 4 4 0 0 0 ######### And here my input file for ph.x ####### &inputph prefix = 'MoS2_BI' fildvscf = 'dvscf' ldisp = .true. fildyn = 'MoS2_BI.dyn' alpha_mix(1) = 0.3 nq1 = 2, nq2 = 2, nq3 = 2, tr2_ph = 1.0d-12 / ######## Is my bilayer wrong? I've come the exact same calculations for Bulk and Monolayer MoS2 and everything went smoothly _______________________________________________ The Quantum ESPRESSO community stands by the Ukrainian people and expresses its concerns about the devastating effects that the Russian military offensive has on their country and on the free and peaceful scientific, cultural, and economic cooperation amongst peoples _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu<http://www.max-centre.eu/>) users mailing list users@lists.quantum-espresso.org<mailto:users@lists.quantum-espresso.org> https://lists.quantum-espresso.org/mailman/listinfo/users _______________________________________________ The Quantum ESPRESSO community stands by the Ukrainian people and expresses its concerns about the devastating effects that the Russian military offensive has on their country and on the free and peaceful scientific, cultural, and economic cooperation amongst peoples _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu<http://www.max-centre.eu/>) users mailing list users@lists.quantum-espresso.org<mailto:users@lists.quantum-espresso.org> https://lists.quantum-espresso.org/mailman/listinfo/users _______________________________________________ The Quantum ESPRESSO community stands by the Ukrainian people and expresses its concerns about the devastating effects that the Russian military offensive has on their country and on the free and peaceful scientific, cultural, and economic cooperation amongst peoples _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu<http://www.max-centre.eu/>) users mailing list users@lists.quantum-espresso.org<mailto:users@lists.quantum-espresso.org> https://lists.quantum-espresso.org/mailman/listinfo/users _______________________________________________ The Quantum ESPRESSO community stands by the Ukrainian people and expresses its concerns about the devastating effects that the Russian military offensive has on their country and on the free and peaceful scientific, cultural, and economic cooperation amongst peoples _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu<http://www.max-centre.eu/>) users mailing list users@lists.quantum-espresso.org<mailto:users@lists.quantum-espresso.org> https://lists.quantum-espresso.org/mailman/listinfo/users _______________________________________________ The Quantum ESPRESSO community stands by the Ukrainian people and expresses its concerns about the devastating effects that the Russian military offensive has on their country and on the free and peaceful scientific, cultural, and economic cooperation amongst peoples _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users _______________________________________________ The Quantum ESPRESSO community stands by the Ukrainian people and expresses its concerns about the devastating effects that the Russian military offensive has on their country and on the free and peaceful scientific, cultural, and economic cooperation amongst peoples _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users
_______________________________________________ The Quantum ESPRESSO community stands by the Ukrainian people and expresses its concerns about the devastating effects that the Russian military offensive has on their country and on the free and peaceful scientific, cultural, and economic cooperation amongst peoples _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users