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<p class="MsoNormal"><span lang="EN-US">Dear MOLPRO users,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I am encountering a problem with dissociation to a higher dissociation channel.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">When dissociating O3 to O2+O, in 1-A’ symmetry, then the MOLPRO calculated CI energy (for fixed O-O distance and angle), is fine up to an O2-O separation of 2.6 A. Until here, the energy is close to the dissociated O2(3-Sigg)
+ O(3-P) energy. At 2.7 A, the calculated energy jumps higher, and stays higher thereafter. It appears that the O2(1-Delta) + O(1-D) level is approached.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">This happens with all CI methods, RS2, MRCI, AQCC and ACPF. Interestingly, the CASSCF energy dissociates to the lowest channel. Dissociation in symmetries, like 1-A”, also moves to a higher channel, although at a larger
distance. <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Reading the literature, there are several MOLPRO calculations described for the 1-A’ dissociation of ozone, covering a large potential energy surface. Apparently, no dissociation problems as described above have been
encountered. This means that there must be a way to avoid this problem.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Any help would be appreciated. <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Fritz Grein<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-CA">Department of Chemistry<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-CA">University of New Brunswick, Canada</span><span lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">--------------------------------------------------------------------<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> R2 ECAS ERS2<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> 2.0 -224.5573513 -225.1020581<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> 2.1 -224.5596135 -225.1015510<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> 2.2 -224.5614908 -225.1012356<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> 2.3 -224.5629154 -225.1009875<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> 2.4 -224.5639408 -225.1007287<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> 2.5 -224.5646529 -225.1003953<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> <b>2.6 -224.5651329 -225.0997375<o:p></o:p></b></span></p>
<p class="MsoNormal"><b><span lang="EN-US"> 2.7 -224.5654847 -225.0134963<o:p></o:p></span></b></p>
<p class="MsoNormal"><span lang="EN-US"> 2.8 -224.5656828 -225.0134413<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> 2.9 -224.5658012 -225.0133640<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> 3.0 -224.5658675 -225.0132738<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">***,o3-scan1<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">memory,100,m<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">symmetry,x<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">angstrom<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">geometry={o1<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> o2,o1,r1<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> o3,o2,r2(i),o1,a}<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">r1=1.22,a=120.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">basis=avtz<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">distance2=[2.0,2.1,2.2,2.3,2.4,2.5,2.6,2.7,2.8,2.9,3.0]<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">i=0<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">do ir2=1,#distance2<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">i=i+1<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">r2(i)=distance2(ir2)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">{hf;maxit,100}<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">{casscf;wf,24,1,0;maxit,40}<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">ecas(i)=energy<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">{rs2;wf,24,1,0;maxit,100;option,maxiti=400}<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">ers2(i)=energy<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">enddo<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">{table,r2,ecas,ers2<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">head,r2,ecas,ers2}<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">----------------------------------------------------------------------<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> <o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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