<html><head></head><body><div class="ydpc5878015yahoo-style-wrap" style="font-family:Helvetica Neue, Helvetica, Arial, sans-serif;font-size:16px;"><div dir="ltr" data-setdir="false">I am trying to calculate the phonon of hBN-AA but it gives negative frequency. </div><div dir="ltr" data-setdir="false">Can anyone check my input files and suggest where should i modify to improve my results</div><div dir="ltr" data-setdir="false">---------------------------------------------------------------------------------------------</div><div dir="ltr" data-setdir="false"><div><div>&CONTROL</div><div> calculation = 'scf'</div><div> prefix = 'hBN_AA'</div><div> pseudo_dir = '/home/suhail/Downloads/qe-6.8/pseudo',</div><div> outdir = './tmp'</div><div>/</div><div>&SYSTEM</div><div> ibrav = 0</div><div> nat = 4</div><div> ntyp = 2</div><div> ecutwfc = 70</div><div> ecutrho = 560</div><div> nbnd = 16</div><div> occupations = 'fixed'</div><div> input_dft = 'PBE'</div><div> vdw_corr = 'DFT-D3'</div><div> assume_isolated = '2D'</div><div>/</div><div>&ELECTRONS</div><div> diagonalization = 'david'</div><div> mixing_beta = 0.70</div><div> conv_thr = 1.0d-10</div><div> electron_maxstep = 200</div><div>/</div><div>ATOMIC_SPECIES</div><div>B 10.811 B.pbe-n-rrkjus_psl.1.0.0.UPF</div><div>N 14.007 N.pbe-n-rrkjus_psl.1.0.0.UPF</div><div>CELL_PARAMETERS angstrom</div><div> 2.504000 0.000000 0.000000</div><div> 1.252000 2.168528 0.000000</div><div> 0.000000 0.000000 23.440000</div><div><br></div><div>ATOMIC_POSITIONS (crystal)</div><div>B 0.0000000000 0.0000000000 0.0119222177</div><div>N 0.3333333300 0.3333333300 0.0119233415</div><div>B 0.0000000000 0.0000000000 0.1699381919</div><div>N 0.3333333300 0.3333333300 0.1699375040</div><div><br></div><div>K_POINTS automatic</div><div>16 16 2 0 0 0</div></div>-----------------------------------------------</div><div dir="ltr" data-setdir="false"><div><div>&INPUT</div><div> prefix = 'hBN_AA'</div><div> outdir = './tmp'</div><div> filhess = 'hBN_AA_D3.hess'</div><div>/</div><div>-----------------------------------</div><div>&INPUTPH</div><div> prefix = 'hBN_AA'</div><div> outdir = './tmp'</div><div> fildyn = 'hBN_AA_D3.dyn'</div><div> tr2_ph = 1.0d-14</div><div> ldisp = .true.</div><div> nq1 = 4</div><div> nq2 = 4</div><div> nq3 = 1</div><div> dftd3_hess = 'hBN_AA_D3.hess'</div><div> search_sym = .false.</div><div>/</div></div>--------------------------------------</div><div dir="ltr" data-setdir="false"><div><div>&INPUT</div><div> fildyn = 'hBN_AA_D3.dyn'</div><div> flfrc = 'hBN_AA_D3.fc'</div><div> zasr = 'simple'</div><div>/</div><div>---------------------------------------------</div><div><br></div><div>&INPUT</div><div> asr = 'simple'</div><div> flfrc = 'hBN_AA_D3.fc'</div><div> flfrq = 'hBN_AA_D3.freq'</div><div> q_in_band_form = .true.</div><div> q_in_cryst_coord = .true.</div><div>/</div><div>4</div><div>0.000000 0.000000 0.000000 60</div><div>0.500000 0.000000 0.000000 60</div><div>0.333333 0.333333 0.000000 60</div><div>0.000000 0.000000 0.000000 1</div></div><br></div><div><br></div><div class="ydpc5878015signature"><div style="font-family:Helvetica Neue, Helvetica, Arial, sans-serif;font-size:16px;"><p>--------------------------------------------------------------------- <br><br><strong><font color="#0000ff" size="4">Dr. Sohail Ahmad</font></strong></p><p><font color="#0000ff">Department of Physics</font></p><p><font color="#0000ff">Faculty of Science, P. O. Box - 9004</font></p><p><font color="#0000ff">King Khalid University</font></p><p><font color="#0000ff">Abha, Saudi Arabia</font><font color="#0000ff"><br></font></p><p>--------------------------------------------------------------------<br><br></p></div></div></div></body></html>