Assistance with Optimization of Potential Curve Calculation for N₂+ Ion

[白光如]

  Dear Molpro Users,

I am currently running CASSCF calculations to compute the potential curve for the N₂+ ion. However, I have encountered small discontinuities in the potential curve near R=1.13 Ang, as shown in the resulting data. I am wondering if anyone can suggest how to optimize the calculation of the potential curve in CASSCF to address this issue.  

  Below is the code I am using:

***,N2plus,potential curve
memory,1024 ,m

geometry={n1;n2,n1,r}
basis=AVQZ
r=1.0 Ang

{hf
orbital,2100.2}
{casscf;
orbital,ignore_error;
OCC,3,1,1,0,3,1,1,0;
CLOSED,
WF,13,1,1;}
do i=1,30
{casscf;
orbital,ignore_error;
OCC,3,1,1,0,3,1,1,0;
CLOSED,
WF,13,5,1;state,14;}
sE1(i)=energy(1);
sE2(i)=energy(2);
sE3(i)=energy(3);
sE4(i)=energy(4);
sE5(i)=energy(5);
sE6(i)=energy(6);
sE7(i)=energy(7);
sE8(i)=energy(8);
sE9(i)=energy(9);
sE10(i)=energy(10);
sE11(i)=energy(11);
sE12(i)=energy(12);
sE13(i)=energy(13);
sE14(i)=energy(14);
rn(i)=r
r=r+0.01
enddo
{table ,rn ,sE1,sE2,sE3,sE4,sE5,sE6,sE7,sE8,sE9,sE10,sE11,sE12,sE13,sE14}

I would appreciate any suggestions or advice on how to improve the stability of the potential curve in these calculations.

Thank you in advance for your help!

  Best regards,
Bai

  

[白光如]

白光如 <bai151...@gmail.com> 于2025年11月12日周三 21:53写道：

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[peterso...@gmail.com]

Daer Bai,

my suggestion in these types of problems is always the same - print and closely inspect the orbitals of your active space as the geometry changes.  At the kink in your curves, an orbital or orbitals is changing character. Once you understand that then you can figure out how to prevent it.  

best regards,  -Kirk

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