<div dir="ltr">
<p class="MsoNormal">Dear all pw users,</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"><span style lang="EN-US">I performed
neb calculations (espresso-5.0.2) with a 25 Ry cutoff and a 6 6 1 k-points grid.
</span></p>
<p class="MsoNormal"><span style lang="EN-US">After
reaching convergence, with the error on each image lower than the selected threshold,
I tried to refine my calculations by increasing the cutoff up to 40 Ry, and by
using more k-points (8 8 1 grid). </span></p>
<p class="MsoNormal"><span style lang="EN-US">Converged neb
(25 Ry)</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>------------------------------
iteration<span style> </span>39
------------------------------</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>cpu =<span style>
</span>0<span style> </span>tcpu =<span style> </span>23906.3<span style>
</span>self-consistency for image<span style> </span>2</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>cpu =<span style>
</span>0<span style> </span>tcpu =<span style> </span>23978.2<span style>
</span>self-consistency for image<span style> </span>4</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>cpu =<span style>
</span>0<span style> </span>tcpu =<span style> </span>24086.9<span style>
</span>self-consistency for image<span style> </span>6</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>cpu =<span style>
</span>0<span style> </span>tcpu =<span style> </span>24200.3<span style>
</span>self-consistency for image<span style> </span>8</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>cpu =<span style>
</span>0<span style> </span>tcpu =<span style> </span>24308.2<span style>
</span>self-consistency for image<span style> </span>10</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>activation energy (->) =<span style> </span>0.894658 eV</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>activation energy (<-) =<span style> </span>0.836243 eV</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>image<span style> </span>energy (eV)<span style> </span>error (eV/A)<span style> </span>frozen</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>1<span style>
</span>-19891.2503277<span style>
</span>0.071116<span style> </span>T</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>2<span style>
</span>-19891.2158612<span style>
</span>0.049589<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>3<span style>
</span>-19891.1523863<span style> </span><span style> </span>0.188484<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>4<span style>
</span>-19891.0150938<span style>
</span>0.162087<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>5<span style>
</span>-19890.9987459<span style>
</span>0.191508<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>6<span style>
</span>-19890.8817497<span style>
</span>0.106483<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>7<span style>
</span>-19890.6985072<span style> </span><span style> </span>0.123973<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>8<span style>
</span>-19890.4818044<span style>
</span>0.093420<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>9<span style>
</span>-19890.3556701<span style>
</span>0.086773<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>10<span style>
</span>-19890.5472740<span style>
</span>0.113798<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>11<span style>
</span>-19891.1235293<span style> </span>0.166418<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>12<span style>
</span>-19891.1919133<span style>
</span>0.070926<span style> </span>T</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>climbing image =<span style> </span>9</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>path length<span style> </span>= 10.335 bohr</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>inter-image distance =<span style> </span>0.940 bohr</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style>
</span>---------------------------------------------------------------------------</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>neb: convergence achieved in<span style> </span>39 iterations</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>NEB<span style> </span>:<span style>
</span>6h39m CPU<span style> </span>6h46m WALL</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>This run was terminated on:<span style> </span>7:53:22<span style>
</span>3Jul2013</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US">=------------------------------------------------------------------------------=</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>JOB DONE.</span></p>
<p class="MsoNormal"><span style lang="EN-US">=------------------------------------------------------------------------------=</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US">So, I
created a new input file with the new values of these parameters (cutoff and
k-points grid), and I copied the atomic coordinates from the .crd file, of the
converged path with 25 Ry and 6 6 1 grid. Then, I ran neb.x with the restart
mode: “from_scratch”. Unfortunately the first iteration of the new neb simulation,
with 40 Ry, showed very large forces.</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>------------------------------
iteration<span style> </span>1
------------------------------</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>cpu =<span style>
</span>0<span style> </span>tcpu =<span style> </span>6.6<span style>
</span>self-consistency for image<span style> </span>1</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>cpu =<span style>
</span>0<span style> </span>tcpu =<span style> </span>281.5<span style>
</span>self-consistency for image<span style> </span>2</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>cpu =<span style>
</span>0<span style> </span>tcpu =<span style> </span>559.0<span style>
</span>self-consistency for image<span style> </span>4</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>cpu =<span style>
</span>0<span style> </span>tcpu =<span style> </span>832.1<span style>
</span>self-consistency for image<span style> </span>6</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>cpu =<span style>
</span>0<span style> </span>tcpu =<span style> </span>1092.8<span style>
</span>self-consistency for image<span style> </span>8</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>cpu =<span style>
</span>0<span style> </span>tcpu =<span style> </span>1365.2<span style>
</span>self-consistency for image<span style> </span>10</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>activation energy (->) =<span style> </span>38.645703 eV</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>activation energy (<-) =<span style> </span>38.552298 eV</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>image<span style> </span>energy (eV)<span style> </span>error (eV/A)<span style> </span>frozen</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>1<span style>
</span>-19892.5055371<span style>
</span>0.008676<span style> </span>T</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>2<span style>
</span>-19892.4796891<span style>
</span>0.244186<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>3<span style>
</span>-19892.4470814<span style>
</span>0.232055<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>4<span style>
</span>-19892.3936725<span style>
</span>0.309786<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>5<span style>
</span>-19892.2598441<span style>
</span>0.174595<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>6<span style>
</span>-19892.2326900<span style>
</span>0.376662<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>7<span style>
</span>-19892.1508214<span style>
</span>0.237737<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span><span style> </span>8<span style>
</span>-19891.9033607<span style>
</span>0.629380<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>9<span style>
</span>-19891.5413520<span style>
</span>1.554399<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>10<span style>
</span>-19890.5368565<span style>
</span>23.555285<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>11<span style>
</span>-19853.8598346<span style>
</span>268.470304<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>12<span style>
</span>-19892.4121325<span style>
</span>0.021811<span style> </span>T</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>climbing image = 11</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>path length<span style> </span>= 11.793 bohr</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>inter-image distance =<span style> </span>1.072 bohr</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US">I don’t
know why so huge forces appeared since my initial path is the converged path with
a 25 Ry cutoff, I think the cutoff may affect forces, but what about the
restart mode “from_scratch”? </span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US">So I even
tried to run the same inputfile with a 25 Ry cutoff and 6 6 1 k-points grid.
Since the initial path is the converged path with 25 Ry and 6 6 1 k-points (copy
and paste from .crd file) , my neb calculation should converge after one
iteration, instead I have large forces:<span style>
</span></span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>------------------------------ iteration<span style> </span>1 ------------------------------</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>cpu =<span style>
</span>0<span style> </span>tcpu =<span style> </span>3.5<span style>
</span>self-consistency for image<span style> </span>1</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>cpu =<span style>
</span>0<span style> </span>tcpu =<span style> </span>268.4<span style>
</span>self-consistency for image<span style> </span>2</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>cpu =<span style>
</span>0<span style> </span>tcpu =<span style> </span>522.8<span style>
</span>self-consistency for image<span style> </span>4</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>cpu =<span style>
</span>0<span style> </span>tcpu =<span style> </span>773.8<span style>
</span>self-consistency for image<span style> </span>6</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span><span style> </span>cpu
=<span style> </span>0<span style>
</span>tcpu =<span style> </span>1020.3<span style> </span>self-consistency for image<span style> </span>8</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>cpu =<span style>
</span>0<span style> </span>tcpu =<span style> </span>1270.4<span style>
</span>self-consistency for image<span style> </span>10</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>activation energy (->) =<span style> </span>38.753850 eV</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>activation energy (<-) =<span style> </span>38.695436 eV</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>image<span style> </span>energy (eV)<span style> </span>error (eV/A)<span style> </span>frozen</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>1<span style>
</span>-19891.2503277<span style>
</span>0.071116<span style> </span>T</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>2<span style>
</span>-19891.2304040<span style>
</span>0.241051<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>3<span style>
</span>-19891.2049038<span style>
</span>0.226864<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>4<span style>
</span>-19891.1588213<span style>
</span>0.318751<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>5<span style>
</span>-19891.0267566<span style>
</span>0.158294<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>6<span style>
</span>-19891.0032580<span style>
</span>0.382541<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>7<span style>
</span>-19890.9283308<span style>
</span>0.232692<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span><span style> </span>8<span style>
</span>-19890.6852427<span style>
</span>0.655155<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>9<span style>
</span>-19890.3234875<span style>
</span>1.547988<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>10<span style>
</span>-19889.3355302<span style>
</span>23.552337<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>11<span style>
</span>-19852.4964773<span style>
</span>269.371205<span style> </span>F</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>12<span style>
</span>-19891.1919133<span style>
</span>0.070926<span style> </span>T</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>climbing image = 11</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>path length<span style> </span>= 11.793 bohr</span></p>
<p class="MsoNormal"><span style lang="EN-US"><span style> </span>inter-image distance =<span style> </span>1.072 bohr</span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US"> </span></p>
<p class="MsoNormal"><span style lang="EN-US">Could
anyone tell me how QE computes forces at iteration number 1, if the restart
mode is from scratch?</span></p>
<p class="MsoNormal"><span style lang="EN-US">How can I
deal with this problem?</span></p>
<p class="MsoNormal"><span style lang="EN-US">Thanks to
all,</span></p>
<p class="MsoNormal"><span style lang="EN-US">Luca Dietz</span></p>
<p class="MsoNormal"><span style lang="EN-US">Ph.D.
student in Chemical Engineering</span></p>
<p class="MsoNormal">Politecnico di Milano, Italy</p>
</div>