Hi All, <br><br>I am running an FCI geometry optimization of BH ground-state. When run, this gives me the result of a minimum at 1.1 Angstrom. But,
if I simply generate the FCI PEC, it is clear that the minimum is not
even close to 1.1 angstroms it is in the vicinity of 1.25 angstroms. I
can't figure out why this discrepancy is occurring since the gradient of the FCI optimization appears quiet reasonable. <br><div class="gmail_quote"><br>The input is: <br>------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
<br>memory,200,m;<br><br>gprint,orbital;<br><br>basis=vdz;<br><br>Geometry<br>angstrom;<br>x,y;<br>B<br>H,1,r1;<br>end<br>r1=1.3426 angstrom;<br><br>{hf<br>wf,6,1,0;<br>save,2200.2;}<br><br>{fci<br>}<br><br>optg;<br>---------------------------------------------------------------------------------------------------------------------------------------------------------------------------
<br><br><br>The input for the PEC is: <br>----------------------------------------------------------------------------------------------------------------------------------------------------------------------------<br>basis=vdz;
<br><br><br>Geometry<br>angstrom;<br>x,y;<br>B<br>H,1,r1;<br>end<br>R_bond=[0.9 0.92 0.94 0.96 0.98 1.0 1.02 1.04 1.06 1.08 1.1 1.12 1.14 1.16 1.18 1.2 1.22 1.24 1.26 1.28 1.3];<br><br>r1=1.3426;<br><br>do i=1,#R_bond<br>

r1=R_bond(i);<br><br>{hf<br>wf,6,1,0;<br>save,2200.2;}<br>E_HF(i)=energy;<br><br>{rccsd(t)<br>}<br><br>E_CCSD(i)=energc;<br>E_CCSDT(i)=energy;<br><br><br>{fci}<br><br>E_fci(i)=energy;<br><br>R_(i)=r1;<br><br>Table,R_,E_HF,E_CCSD,E_CCSDT,E_FCI;
<br>enddo<br>------------------------------------------------------------------------------------------------------------------------------------------------------------------------------<br><br>Any insight would be most helpful. 
<br><br>Doran Bennett<br><font color="#888888"><br clear="all"><br>-- <br>Web Page: <a href="http://bennett.doran.googlepages.com" target="_blank">http://bennett.doran.googlepages.com</a>
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