It seems that now you are using pseusopotentials generated with different functionals (pz and pbe).<br>In my experience it is hard to converge ultrasoft with respect to ecutrho: at a certain point the total enegy starts<br>
oscillating or it goes down very slowly. This could be the reason of the behavior that you see, namely the<br>results for different ecutwfc does not converge because none of them is fully converged with respect to<br>ecutrho. From this point of view I found that rrkj ultrasoft have a much better behavior. If I remember well they are optimized to use a smaller number of plane-waves to describe the augmentation<br>
charge. I would follow the suggestion "So usually it is better to check the convergence of the quantity you are interested in"<br>Dario<br><br><div class="gmail_quote">On Tue, Nov 11, 2008 at 12:05 PM, Timothy Mason <span dir="ltr"><<a href="mailto:thmason24@yahoo.com">thmason24@yahoo.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><table border="0" cellpadding="0" cellspacing="0"><tbody><tr><td style="font-family: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; font-size: inherit; line-height: inherit; font-size-adjust: inherit; font-stretch: inherit;" valign="top">
I have not attempted your suggestion however I did trade out the PSPS with different PSPSs. I'm now using <br><br> Li.pz-n-vbc.UPF<br> N.pbe-rrkjus.UPF<br> H.pbe-rrkjus.UPF<br><br>and they seem to converge nicely.<br>
<br>is there problem with the ones I was using? here they are for reference<div class="Ih2E3d"><br><br>Li 6.941000 Li.pbe-n-van.UPF<br>N 14.006740 N.pbe-van_ak.UPF<br>H 1.007940 H.pbe-van_ak.UPF<br><br></div>I'm not sure of the best way to select them from the website.<br>
<br>thanks for the help.<br><br><br><br><br><br><br><br>--- On <b>Thu, 11/6/08, <a href="mailto:prasenjit.jnc@gmail.com" target="_blank">prasenjit.jnc@gmail.com</a> <i><<a href="mailto:prasenjit.jnc@gmail.com" target="_blank">prasenjit.jnc@gmail.com</a>></i></b> wrote:<br>
<blockquote style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; padding-left: 5px;">From: <a href="mailto:prasenjit.jnc@gmail.com" target="_blank">prasenjit.jnc@gmail.com</a> <<a href="mailto:prasenjit.jnc@gmail.com" target="_blank">prasenjit.jnc@gmail.com</a>><br>
Subject: Re: Re: [Pw_forum] Total energy does not
coverge with ecut<br>To: "Timothy Mason" <<a href="mailto:thmason24@yahoo.com" target="_blank">thmason24@yahoo.com</a>>, "PWSCF Forum" <<a href="mailto:pw_forum@pwscf.org" target="_blank">pw_forum@pwscf.org</a>><br>
Date: Thursday, November 6, 2008, 4:10 PM<div><div></div><div class="Wj3C7c"><br><br><div>Sometimes it is also difficult to converge the total energy. So usually it is better to check the convergence of the quantity you are interested in.<br>
<br>But anyway it is really strange that total energy doesn't converge at such abnormally high cut off values.<br><br>Did you test the pseudopotentials individually?? For eg. did you try calculating the bond lengths of say a nitrogen molecule & see how the results are??<br>
<br>With regards,<br><br>Prasenjit.<br><br>On Nov 6, 2008 5:45pm, Timothy Mason <<a href="mailto:thmason24@yahoo.com" target="_blank">thmason24@yahoo.com</a>> wrote:<br>> Dear Lorenzo,<br>> <br>> here are results for the lower energy range. Still doesn't seem to be converging.<br>
> <br>> ecut energy energy differnce<br>> 30 -48.19258627 <br>> 35
-48.19503183 0.00244556<br>> 40 -48.197306 0.00227417<br>> 45 -48.20217820 0.0048722<br>> <br>> thanks<br>> <br>> --- On Thu, 11/6/08, Lorenzo Paulatto <a href="mailto:paulatto@sissa.it" target="_blank">paulatto@sissa.it</a>> wrote:<br>
> From: Lorenzo Paulatto <a href="mailto:paulatto@sissa.it" target="_blank">paulatto@sissa.it</a>><br>> Subject: Re: [Pw_forum] Total energy does not coverge with ecut<br>> To: <a href="mailto:thmason24@yahoo.com" target="_blank">thmason24@yahoo.com</a>, "PWSCF Forum" <a href="mailto:pw_forum@pwscf.org" target="_blank">pw_forum@pwscf.org</a>><br>
> Date: Thursday, November 6, 2008, 10:08 AM<br>> <br>> Timothy Mason ha scritto:<br>> ><br>> > Gentlemen,<br>> ><br>> > My structures do not see to be converging with increased ecutwfc. <br>
> > I'm setting ecutrho to ecutwfc * 12 and using US PP. below is a<br>> > table of ecut values vs energies vs difference from previous steps<br>> > followed by my input file followed by part of the output file. It<br>
> > appears to begin to converge and 120 ecut but then
jumps at 130 and<br>> > then more at 140.<br>> ><br>> Dear Timothy,<br>> these are ridiculous cutoff energy for ultrasoft pseudopotentials - they<br>> are very high for norm-conserving too! I suspect the presence of a<br>
> high-energy ghost-state in one of the pseudopotential; these kind<br>> of<br>> states aren't usually harmful but can suddenly pop-up under some<br>> specifics conditions like high pressure or very high cutoff.<br>
> <br>> What is happening when you try some reasonable cutoff in the 20-50 Ry range?<br>> <br>> regards<br>> <br>> -- <br>> Lorenzo Paulatto<br>> SISSA & DEMOCRITOS (Trieste)<br>> phone: +39 040 3787 511<br>
> skype: paulatz<br>> www: <a href="http://people.sissa.it/%7Epaulatto/" target="_blank">http://people.sissa.it/~paulatto/</a><br>> <br>> Due to budget cuts approved by Italian Minister of Finance and Italian<br>
> Minister "for" Education, University and Research this may be the<br>> last<br>> email
you receive from me.<br>> <br>> Please send any future correspondence, possibly via pigeon, to<br>> mr. Lorenzo Paulatto<br>> under Roiano Railway Bridge - Pillar 2<br>> 34136, Trieste<br>> <br>> Donations in food, coins, booze and processor time are warmly welcome.<br>
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