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Hi,
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<div class="">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 class="">regards,</div>
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<div class="">-Kirk</div>
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<div class="">On Dec 8, 2017, at 4:54 PM, Shiblee Ratan <<a href="mailto:shibleeratan@gmail.com" class="">shibleeratan@gmail.com</a>> wrote:</div>
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<div class="">Hello Molpro Experts,<br class="">
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Is it possible to do an <b class="">MRCC Kallay CCSDT(Q) energy</b> calculation for an
<b class="">open-shell ROHF reference</b>? The error message below keeps giving me hope:<br class="">
<br class="">
<i class="">Executing mrcc...<br class="">
<br class="">
<span style="background-color:rgb(255,255,0)" class=""><span style="" class=""><span style="background-color:rgb(238,238,238)" class=""> Approximate CC methods are not implemented for standard ROHF orbitals!</span><br class="">
Use semicanonical orbitals!</span></span><br class="">
<br class="">
Fatal error in mrcc.<br class="">
? Error<br class="">
? Fatal error in mrcc.<br class="">
? The problem occurs in MRCC</i><br class="">
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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 class="">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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<br class="">
CCSDT(Q) energy works fine with <u class="">UHF reference</u> though. <br class="">
<br class="">
Any help or suggestion to make MRCC Kallay's <b class="">CCSDT(Q)</b> work with the
<b class="">ROHF reference</b> will be greatly appreciated.<br class="">
<br class="">
Input file I used is:<br class="">
<br class="">
-----------------------------------------------------------------------------------------------------------<br class="">
memory,768,m<br class="">
gthresh,energy=1.0d-12,orbital=1.0d-12,oneint=1.0d-16,twoint=1.0d-16<br class="">
Geometry = {<br class="">
H1<br class="">
N , H1 , rNH<br class="">
H2 , N , rNH , H1 , aHNH<br class="">
}<br class="">
<br class="">
rNH = 1.04100000 Ang<br class="">
aHNH = 100.72710000 Degree<br class="">
<br class="">
basis=cc-pvdz<br class="">
<br class="">
{rhf;maxit,100<br class="">
wf,nelec=9,sym=2,spin=1<br class="">
<b class="">orbital,type=semicanonical or pseudo-canonical</b> <span style="background-color:rgb(255,255,0)" class="">
<--- Tried these and many other combinations but did not make any difference</span><br class="">
occ,3,1,1,0;closed,3,0,1,0}<br class="">
<br class="">
mrcc,method=ccsdt(q)<br class="">
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<div class=""><font size="2" class="">-----------------------------------------------------------------------------------------<br class="">
<b class="">Dr. Shiblee Ratan Barua<br class="">
</b><i class="">Postdoctoral Research Fellow<br class="">
</i><span class=""><span class="">Rm S162, Bld 34</span></span><br class="">
NASA Goddard Space Flight Center<br class="">
</font></div>
<div class=""><font size="2" class="">8800 Greenbelt Rd, Greenbelt, MD USA 20771<i class=""><br class="">
Email</i>: <a href="mailto:shibleeratan@gmail.com" target="_blank" class="">shibleeratan@gmail.com</a>,
<span class=""><a href="mailto:shiblee.barua@nasa.gov" target="_blank" class="">shiblee.barua@nasa.gov</a></span></font></div>
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