<div dir="ltr"><div><div><div><div>Dear Kirk,<br><br></div>That was a great hack! I followed your suggestion and it seems like UHF maxit=1 retains the preceding ROHF orbital properties; i.e. the orbital occupation and orbital energies for ROHF and UHF look identical in the output file. I think this is a good guess reference for the mrcc CCSDT(Q) job that comes later. <br><br>Also, since I will eventually be calculating relative energies, any error arising from the hack is expected to cancel out.<br><br></div>I have included the input here for people who might be interested:<br><br>------------------------------------------------------------------------------------------------------------------------------------------------------------<br>memory,768,m<br>gthresh,energy=1.0d-12,orbital=1.0d-12,oneint=1.0d-16,twoint=1.0d-16<br>Geometry = {<br>N<br>}<br><br>basis=cc-pVDZ<br><br>{rhf;maxit,100<br>wf,nelec=7,sym=8,spin=3<br>occ,2,1,1,0,1;closed,2}<br><br>{uhf;maxit,1<br>wf,nelec=7,sym=8,spin=3<br>occ,2,1,1,0,1;closed,2}<br><br>!NOTE: MRCC works only with UHF reference. So, here we will trick MRCC by doing only one UHF iteration right after ROHF.<br><br>{mrcc,method=ccsdt(q)<br>orbital,ignore_error=1}<br><br>----------------------------------------------------------------------------------------------------------------------------------------------------------------- <br><br></div>Thanks,<br></div>Shiblee<br><br></div><div class="gmail_extra"><br clear="all"><div><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div><font size="2">-----------------------------------------------------------------------------------------<br><b>Dr. Shiblee Ratan Barua<br></b><i>Postdoctoral Research Fellow<br></i><span><span>Rm S162, Bld 34</span></span><br>NASA Goddard Space Flight Center<br></font></div><div><font size="2">8800 Greenbelt Rd, Greenbelt, MD USA 20771<i><br>Email</i>: <a href="mailto:shibleeratan@gmail.com" target="_blank">shibleeratan@gmail.com</a>, <span><a href="mailto:shiblee.barua@nasa.gov" target="_blank">shiblee.barua@nasa.gov</a></span></font></div></div><span></span></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div>
<br><div class="gmail_quote">On Mon, Dec 11, 2017 at 11:27 AM, Peterson, Kirk <span dir="ltr"><<a href="mailto:kipeters@wsu.edu" target="_blank">kipeters@wsu.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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Hi,
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<div>one hack you can use is to run your ROHF orbitals through 1 iteration of the UHF program (maxit,1) and then use these in mrcc. You’ll need to add the ignore_error option to the orbital directive in mrcc. This is not entirely rigorous since some
terms are then missing in the (Q), but it does generally give very reasonable results.</div>
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<div>regards,</div>
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<div>-Kirk</div>
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<div>On Dec 8, 2017, at 4:54 PM, Shiblee Ratan <<a href="mailto:shibleeratan@gmail.com" target="_blank">shibleeratan@gmail.com</a>> wrote:</div>
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<div>Hello Molpro Experts,<br>
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Is it possible to do an <b>MRCC Kallay CCSDT(Q) energy</b> calculation for an
<b>open-shell ROHF reference</b>? The error message below keeps giving me hope:<br>
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<i>Executing mrcc...<br>
<br>
<span style="background-color:rgb(255,255,0)"><span><span style="background-color:rgb(238,238,238)"> Approximate CC methods are not implemented for standard ROHF orbitals!</span><br>
Use semicanonical orbitals!</span></span><br>
<br>
Fatal error in mrcc.<br>
? Error<br>
? Fatal error in mrcc.<br>
? The problem occurs in MRCC</i><br>
<br>
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I am trying to calculate the CCSDT(Q) energy for a (doublet-B1) NH2 molecule. Tried a lot of things, but it seems like there is no option to force Molpro to generate
<b>semicanonical ROHF orbitals</b> as the error message above wants. ROHF keeps generating canonical/standard orbitals in record file 2100.2.
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CCSDT(Q) energy works fine with <u>UHF reference</u> though. <br>
<br>
Any help or suggestion to make MRCC Kallay's <b>CCSDT(Q)</b> work with the
<b>ROHF reference</b> will be greatly appreciated.<br>
<br>
Input file I used is:<br>
<br>
------------------------------<wbr>------------------------------<wbr>------------------------------<wbr>-----------------<br>
memory,768,m<br>
gthresh,energy=1.0d-12,<wbr>orbital=1.0d-12,oneint=1.0d-<wbr>16,twoint=1.0d-16<br>
Geometry = {<br>
H1<br>
N , H1 , rNH<br>
H2 , N , rNH , H1 , aHNH<br>
}<br>
<br>
rNH = 1.04100000 Ang<br>
aHNH = 100.72710000 Degree<br>
<br>
basis=cc-pvdz<br>
<br>
{rhf;maxit,100<br>
wf,nelec=9,sym=2,spin=1<br>
<b>orbital,type=semicanonical or pseudo-canonical</b> <span style="background-color:rgb(255,255,0)">
<--- Tried these and many other combinations but did not make any difference</span><br>
occ,3,1,1,0;closed,3,0,1,0}<br>
<br>
mrcc,method=ccsdt(q)<br>
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<div><font size="2">------------------------------<wbr>------------------------------<wbr>-----------------------------<br>
<b>Dr. Shiblee Ratan Barua<br>
</b><i>Postdoctoral Research Fellow<br>
</i><span><span>Rm S162, Bld 34</span></span><br>
NASA Goddard Space Flight Center<br>
</font></div>
<div><font size="2"><a href="https://maps.google.com/?q=8800+Greenbelt+Rd,+Greenbelt,+MD+USA+20771&entry=gmail&source=g">8800 Greenbelt Rd, Greenbelt, MD USA 20771</a><i><br>
Email</i>: <a href="mailto:shibleeratan@gmail.com" target="_blank">shibleeratan@gmail.com</a>,
<span><a href="mailto:shiblee.barua@nasa.gov" target="_blank">shiblee.barua@nasa.gov</a></span></font></div>
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