<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">David,<div><br></div><div>it looks to me that you're getting stuck into a few local minima. Do these different calculations converge to different structures? How different are the energies at the starting geometries? I would strongly recommend printing the orbitals and taking a careful look. You could also try doing a CASSCF calculation (print the orbitals and CI vector) to see how things should really be occupied.</div><div><br></div><div>regards,</div><div><br></div><div>Kirk</div><div><br></div><div><br><div><div>On Nov 3, 2010, at 6:19 AM, David Danovich wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div dir="ltr"><div style="MARGIN: 0in 0in 0pt" class="MsoPlainText"><font face="Courier New">Hello,</font></div>
<div style="MARGIN: 0in 0in 0pt" class="MsoPlainText"><font face="Courier New"></font> </div>
<div style="MARGIN: 0in 0in 0pt" class="MsoPlainText"><font face="Courier New">I am calculating CuAu2 molecule in high spin state (4B2 state) using B3LYP method. Below you can find three different possibilities I have used in the calculations. In the first one 1) I have calculated first HF wave function and used it as a guess for DFT calculation. Energy I got was -468.86467917 au. In the second calculation 2) I directly have calculated B3LYP without HF wave function. The energy I got was -468.83995914 au. In the third calculation 3) I first have done B3LYP calculation for state (4A2) and then used it as a guess for the calculations of 4B2. The energy I got was <br>
-468.85824088 au. As you can see there is quite large difference in energy for the same state. I was trying to use different grids but it does not solved the problem. In my opinion result should not depend on the guess so drastically. What can be a solution for this problem?<br>
<br>Thank you in advance David</font></div>
<div style="MARGIN: 0in 0in 0pt" class="MsoPlainText"><font face="Courier New"></font> </div>
<div style="MARGIN: 0in 0in 0pt" class="MsoPlainText"><font face="Courier New">1)<br><br>***, Peterson PP tz basis set<br>memory,250,m<br><span style="mso-spacerun: yes"> </span>r =<span style="mso-spacerun: yes"> </span>2.72684681 ang;<br>
<span style="mso-spacerun: yes"> </span>a = 60.65125012 degree;<br>geometry={Cu1;<span style="mso-spacerun: yes"> </span>!z-matrix geometry input<br><span style="mso-spacerun: yes"> </span></font><font face="Courier New"><span style="mso-ansi-language: FR" lang="FR">Au2,Cu1,r;<br>
<span style="mso-spacerun: yes"> </span>Au3,Cu1,r,Au2,a;<br><span style="mso-spacerun: yes"> </span>}<br>basis=cc-pVTZ-PP<br><br>{hf,maxit=500;<br>wf,57,3,3}<br><br>{rks,b3lyp3,maxit=500;<br>wf,57,3,3}<br>
<br></span>optg<br><br><span style="mso-spacerun: yes">Total energy </span>-468.86467917 au<br>____________________________________________________<br><br>2)<br>***, Peterson PP tz basis set <br>memory,250,m<br><span style="mso-spacerun: yes"> </span>r =<span style="mso-spacerun: yes"> </span>2.72684681 ang;<br>
<span style="mso-spacerun: yes"> </span>a = 60.65125012 degree;<br>geometry={Cu1;<span style="mso-spacerun: yes"> </span>!z-matrix geometry input<br><span style="mso-spacerun: yes"> </span><span style="mso-spacerun: yes"> </span></font><font face="Courier New"><span style="mso-ansi-language: FR" lang="FR">Au2,Cu1,r;<br>
<span style="mso-spacerun: yes"> </span>Au3,Cu1,r,Au2,a;<br><span style="mso-spacerun: yes"> </span>}<br>basis=cc-pVTZ-PP<br><br>{ks,b3lyp3,maxit=500;<br></span>shift,-0.1,0.0;<br>wf,57,3,3}<br><br>optg<br>
<br>Total energy -468.83995914 au<br><br>______________________________________________________<br><br>3)<br>***, Peterson PP tz basis set <br>memory,250,m<br><span style="mso-spacerun: yes"> </span>r = <span style="mso-spacerun: yes"> </span>2.72684681 ang;<br>
<span style="mso-spacerun: yes"> </span>a = 60.65125012 degree;<br>geometry={Cu1;<span style="mso-spacerun: yes"> </span>!z-matrix geometry input<br><span style="mso-spacerun: yes"> </span></font><font face="Courier New"><span style="mso-ansi-language: FR" lang="FR">Au2,Cu1,r;<br>
<span style="mso-spacerun: yes"> </span>Au3,Cu1,r,Au2,a;<br><span style="mso-spacerun: yes"> </span>}<br><br>! cc-pVTZ-PP<br><br>basis=cc-pVTZ-PP<br><br>{ks,b3lyp3,maxit=500;<br>wf,57,4,3}<br><br>{ks,b3lyp3,maxit=500;<br>
</span>shift,-1.0,0.0;<br>wf,57,3,3}<br><br>optg<br><br>Total energy -468.85824088 au</font><br><br></div></div>
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