<div dir="ltr">Dear Dr. Lorenzo,<div><br></div><div>I have tried all possible paths from octa-octa but still I get the same value. The full input script I am using to calculate activation energy is as follows .</div><div><div><div>BEGIN</div><div>BEGIN_PATH_INPUT</div><div>&PATH</div><div> string_method = 'neb',</div><div> restart_mode = 'restart',</div><div> nstep_path = 60,</div><div> ds = 2.D0,</div><div> opt_scheme = "broyden",</div><div> num_of_images = 7,</div><div>first_last_opt = .TRUE.,</div><div> minimum_image = .TRUE.,</div><div> k_max = 0.3D0,</div><div> k_min = 0.2D0,</div><div> path_thr = 0.01D0,</div><div>/</div><div>END_PATH_INPUT</div><div>BEGIN_ENGINE_INPUT</div><div>&control</div><div> calculation='relax',</div><div> prefix='NiHeN',</div><div> tprnfor =.t.,</div><div> pseudo_dir = '/home/ras256/nebH',</div><div> outdir='/home/ras256/nebH/tmp',</div><div>/</div><div> &SYSTEM</div><div> nat = 5,</div><div> ntyp = 2,</div><div> degauss = 0.018,</div><div> nbnd = 48,</div><div> nspin = 2,</div><div> starting_magnetization(1) = 0.0,</div><div> starting_magnetization(2) = 0.5,</div><div> ecutwfc = 45,</div><div> ibrav = 0,</div><div> occupations = 'smearing',</div><div> smearing = 'gauss',</div><div> ecutrho = 700,</div><div> /</div><div> &ELECTRONS</div><div> conv_thr = 1e-08,</div><div> mixing_beta = 0.7,</div><div> mixing_mode = 'local-TF',</div><div> /</div><div>&IONS</div><div> /</div><div>&CELL</div><div>/</div><div>ATOMIC_SPECIES</div><div> H 1.00 H.pbe-vbc.UPF</div><div> Ni 58.6934 Ni.pbe-nd-rrkjus.UPF</div><div>K_POINTS automatic</div><div> 6 6 6 0 0 0</div><div>BEGIN_POSITIONS</div><div>FIRST_IMAGE</div><div>ATOMIC_POSITIONS crystal</div><div> Ni 0 0 0</div><div> Ni 0 0.5 0.5</div><div> Ni 0.5 0 0.5</div><div> Ni 0.5 0.5 0</div><div> H 0.5 0.5 0.5</div><div>LAST_IMAGE</div><div>ATOMIC_POSITIONS crystal</div><div> Ni 0 0 0</div><div> Ni 0 0.5 0.5</div><div> Ni 0.5 0 0.5</div><div> Ni 0.5 0.5 0</div><div> H 0.5 0.0 0.0</div><div>END_POSITIONS</div><div>CELL_PARAMETERS angstrom</div><div> 3.522900 0.000000 0.000000</div><div> 0.000000 3.522900 0.000000</div><div> 0.000000 0.000000 3.522900</div><div>END_ENGINE_INPUT</div><div>END</div><div><span style="font-size:12.8000001907349px">> Hi,</span><br style="font-size:12.8000001907349px"><span style="font-size:12.8000001907349px">></span><br style="font-size:12.8000001907349px"><span style="font-size:12.8000001907349px">> I am using neb to calculate activation energy of hydrogen in unit cell</span><br style="font-size:12.8000001907349px"><span style="font-size:12.8000001907349px">> of nickel. I have placed hydrogen in octahedral position and I am</span><br style="font-size:12.8000001907349px"><span style="font-size:12.8000001907349px">> moving it to another octahedral position as shown below. My question</span><br style="font-size:12.8000001907349px"><span style="font-size:12.8000001907349px">> is whether neb can calculates transition state which is tetrahedral</span><br style="font-size:12.8000001907349px"><span style="font-size:12.8000001907349px">> site?. I have used a path_thr of 0.01eV with 7 images. I have</span><br style="font-size:12.8000001907349px"><span style="font-size:12.8000001907349px">> calculated the activation energy which I am getting is 1.05 eV as</span><br style="font-size:12.8000001907349px"><span style="font-size:12.8000001907349px">> shown in output, whereas the experiments indicate 0.42.</span><br style="font-size:12.8000001907349px"><span style="font-size:12.8000001907349px">> Are you sure that initial and final positions are first-neighbours?</span><br style="font-size:12.8000001907349px"><span style="font-size:12.8000001907349px">> The NEB code should produce an axsf file that you can examine with</span><br style="font-size:12.8000001907349px"><span style="font-size:12.8000001907349px">> xcrysden to check the path.</span><br style="font-size:12.8000001907349px"><span style="font-size:12.8000001907349px">></span><span style="font-size:12.8000001907349px">If it is ok, there are innumerable other possible sources of error, most</span><br style="font-size:12.8000001907349px"><span style="font-size:12.8000001907349px">of which we cannot guess from the very limited input/output you provide</span><br></div></div>-- <br><div class="gmail_signature">Thanks<div>Ravi</div></div>
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