Please here is an image of the band structure plot I had for 3x3x1pristine graphene supercell. Is it normal to have this? And why do I see the linearity around the K high symmetry point in papers?
https://tinyurl.com/3x3image And this is the content of input files: SCF ==== &CONTROL calculation = "scf" outdir = "../temp/" prefix = "project" pseudo_dir = "../pseudo" restart_mode = "from_scratch" / &SYSTEM a = 7.4017956849 c = 18 degauss = 1.00000e-02 ecutrho = 3.60000e+02 ecutwfc = 9.00000e+01 ibrav = 4 nat = 18 ntyp = 1 occupations = "smearing" smearing = "marzari-vanderbilt" / &ELECTRONS conv_thr = 1.00000e-08 mixing_beta = 7.00000e-01 diagonalization = "david" electron_maxstep = 200 / K_POINTS {automatic} 15 15 1 0 0 0 ATOMIC_SPECIES C 12.01070 C.pbe-n-kjpaw_psl.1.0.0.UPF ATOMIC_POSITIONS {crystal} C 0.0000000000 0.0000000000 0.2499999997 C 0.1111111269 0.2222222537 0.2499999994 C -0.0000009773 0.3333325787 0.2499999998 C 0.1111119864 0.5555564932 0.2499999999 C -0.0000009773 0.6666664440 0.2499999998 C 0.1111111269 0.8888888731 0.2499999994 C 0.3333335560 0.0000009773 0.2499999998 C 0.4444443680 0.2222221840 0.2500000005 C 0.3333335560 0.3333325787 0.2499999998 C 0.4444435068 0.5555564932 0.2499999999 C 0.3333330000 0.6666670000 0.2499999993 C 0.4444435068 0.8888880136 0.2499999999 C 0.6666674213 0.0000009773 0.2499999998 C 0.7777778160 0.2222221840 0.2500000005 C 0.6666670000 0.3333330000 0.2500000025 C 0.7777778160 0.5555556320 0.2500000005 C 0.6666674213 0.6666664440 0.2499999998 C 0.7777777463 0.8888888731 0.2499999994 Bands ====== &CONTROL calculation = "bands" outdir = "../temp/" prefix = "project" pseudo_dir = "../pseudo" / &SYSTEM a = 7.4017956849 c = 18 degauss = 1.00000e-02 ecutrho = 3.60000e+02 ecutwfc = 9.00000e+01 ibrav = 4 nat = 18 ntyp = 1 nbnd = 144 occupations = "smearing" smearing = "marzari-vanderbilt" / &ELECTRONS conv_thr = 1.00000e-08 mixing_beta = 7.00000e-01 diagonalization = "david" electron_maxstep = 200 / K_POINTS {crystal_b} 4 0.0000000000 0.0000000000 0.0000000000 50 !G 0.3333333333 0.3333333333 0.0000000000 30 !K 0.5000000000 0.0000000000 0.0000000000 40 !M 0.0000000000 0.0000000000 0.0000000000 0 !G ATOMIC_SPECIES C 12.01070 C.pbe-n-kjpaw_psl.1.0.0.UPF ATOMIC_POSITIONS {crystal} C 0.0000000000 0.0000000000 0.2499999997 C 0.1111111269 0.2222222537 0.2499999994 C -0.0000009773 0.3333325787 0.2499999998 C 0.1111119864 0.5555564932 0.2499999999 C -0.0000009773 0.6666664440 0.2499999998 C 0.1111111269 0.8888888731 0.2499999994 C 0.3333335560 0.0000009773 0.2499999998 C 0.4444443680 0.2222221840 0.2500000005 C 0.3333335560 0.3333325787 0.2499999998 C 0.4444435068 0.5555564932 0.2499999999 C 0.3333330000 0.6666670000 0.2499999993 C 0.4444435068 0.8888880136 0.2499999999 C 0.6666674213 0.0000009773 0.2499999998 C 0.7777778160 0.2222221840 0.2500000005 C 0.6666670000 0.3333330000 0.2500000025 C 0.7777778160 0.5555556320 0.2500000005 C 0.6666674213 0.6666664440 0.2499999998 C 0.7777777463 0.8888888731 0.2499999994 From: "David Yao ANSI via users" <[email protected]> To: [email protected] Sent: Wednesday, May 31, 2023 5:33:43 PM Subject: [QE-users] Linear Dispersion Behavior of Graphene Supercells: Seeking Explanations and Solutions Dear All, In studying quantum capacitance of doped graphene, I recently made band structure calculations on pristine graphene using supercells of varying sizes. However, I encountered an unexpected result when increasing the supercell size from 2x2x1 to 4x4x1: the linear dispersion behavior around the K - high symmetry point gradually disappeared. This came as a surprise to me since previous articles I read reported a linear dispersion around the K point for similar supercell sizes. I did some also with a gamma Brillouin zone sampling during scf but had same results. What are possible reasons behind this and potential approaches to achieve the desired linear behavior in supercell calculations? Are there specific techniques or considerations that need to be taken into account when working with larger supercells of graphene? Thank you in advance for your assistance and expertise. Regards, David Ansi Master's student University of Sci. and Tech.(KNUST), Ghana _______________________________________________ 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 [email protected] 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 [email protected] https://lists.quantum-espresso.org/mailman/listinfo/users
