Dear Quantum Espresso Community, I am trying to perform DFT calculations with Van der Waals corrections on non-metal dimers at different distances to obtain a potential energy curve. In my results however, I noticed an unusual sharp jump in the tail of the potential energy curve which I cannot explain for non metals dimers of Carbon, Nitrogen and Silicon. Metallic dimers however did not exhibit such behavior. What is the reason for such behavior? Could this be an inherent problem with QE?
Please see below a sample of my input script and attached a copy of my results for Nitrogen dimers. &CONTROL calculation = 'scf' , wf_collect = .true. , outdir = './' , pseudo_dir = './' , prefix = 'n_dimer-df2_1.70' , disk_io = 'none', / &SYSTEM ibrav = 0, celldm(1)= 1.88972687, ntyp = 1, nat = 2, ecutwfc = 90, ecutrho = 900, nosym = .FALSE. input_dft = vdw-df2 occupations = 'smearing', smearing = 'gauss', degauss = 0.0001, one_atom_occupations = .TRUE., nspin = 2, starting_magnetization(1) = 1, starting_magnetization(2) = 1, / &ELECTRONS electron_maxstep = 1000, conv_thr = 1d-7, mixing_mode = 'plain', mixing_beta = 0.3, / &IONS / / &CELL / CELL_PARAMETERS cubic 20.000000000 0.0000000000 0.0000000000 0.0000000000 20.000000000 0.0000000000 0.0000000000 0.0000000000 20.000000000 ATOMIC_SPECIES N 14.0067 N.pbe-n-kjpaw_psl.1.0.0.UPF ATOMIC_POSITIONS { angstrom } N 0.0 0.0 0.0 N 0.0 0.0 1.70 K_POINTS gamma [image: pec.png] Thank you in advance! Kevin Kayang
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