[molpro-user] LVECT Error in MS-CASPT2 - any options to help?

[Seth Olsen]

Dear Prof. Werner,

I'm not sure I understand.  I have used this same executable to perform 
similar calculations on larger systems without this error.  This 
calculation employs 250 contracted basis functions.  The error appears 
in the output of rs2 immediately after the declaration of the size of 
the p-space, not during integration.  Is the overlap in question really 
basis overlap or overlap of pair configurations?

Best Regards,

Seth

H. -J. Werner wrote:
> The vector length is maxbfn. So you can increase the max number
> of basis functions at configure time and then recompile. The
> max number of basis functions is 4095. Alternatively, increase
> the parameter lenvc in common/cvectr in some other way.
> Joachim Werner
> On Di, 26 Sep 2006, Seth Olsen wrote:
>
>   
>> Hi Molpro-Users, 
>>
>> A recent ms-mr-caspt2 job with 5 mixed states died with the error:
>>
>> ?WARNING: SMALL EIGENVALUE OF PAIR OVERLAP MATRIX:  0.9597D-07
>> n=                  2638   lvec=                  2000
>> ? Error
>> ? LVECT TOO SMALL
>> ? The problem occurs in SMH
>>
>>  But it is not clear to me from the manual what options/thresholds I 
>> might deploy to  limit the number of doubles to  avoid  the  
>> near-singularity.  Could somebody suggest what options I might consider?
>>
>> Cheers,
>>
>> Seth
>>
>>     
>
>