Author Topic: Back Engine Exception : Diagonalization error  (Read 4318 times)

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Offline perfetti

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Back Engine Exception : Diagonalization error
« on: September 29, 2012, 15:50 »
Dear everyone,
       I am trying to calculate the total energy of a system, however, I've always got this error:* Back Engine Exception : Diagonalization error, overlap matrix not positive definite. This may be caused by atoms that are too close to each other or situated in equivalent positions, or (in the Extended Huckel model) a too low value of interaction_max_range
** Location of Exception : mathutils.cpp:1084



This application has requested the Runtime to terminate it in an unusual way.
Please contact the application's support team for more information.
+----------------------------------------------------------------

the input script is attatched. Could anyone give me any advice?
      Thank you.
      Best regards.


Offline Anders Blom

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Re: Back Engine Exception : Diagonalization error
« Reply #1 on: September 29, 2012, 22:11 »
Did you read the error message? A simple check in the Builder (using Select>Close Neighbors) shows that all (or most at least) the Cu atoms are duplicated, so you have - as the message suggests - atoms on top of each other.

Offline zhangguangping

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Re: Back Engine Exception : Diagonalization error
« Reply #2 on: April 23, 2016, 17:05 »
Did you read the error message? A simple check in the Builder (using Select>Close Neighbors) shows that all (or most at least) the Cu atoms are duplicated, so you have - as the message suggests - atoms on top of each other.

Your advising function is useful. Ineed, when using move-fuse function, one sometime forget to click fuse, then there would be two atoms superposing and resulting this error.

By the way, in this thread http://quantumwise.com/forum/index.php?topic=1904.msg9335#msg9335, you suggest to increase the interaction max range,

So, I wonder if this error is not caused by two atoms too close but from the interaction max range, can you please tell the relationship between the interaction max range and the basis set oribtal range which we can see from the basis setting (the radial part).
If say, the max range value of basis set for all the atoms in the calcualtion is r1, we can safely set the interaction max range to be r2 > 2*r1 to eleminte this kind of error?

With best regards,

Guangping
With best regards,

Guangping

Offline Anders Blom

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Re: Back Engine Exception : Diagonalization error
« Reply #3 on: April 24, 2016, 07:04 »
This error is in 99.99% of all cases caused by atoms overlapping. Besides, the other case is only for the extended Huckel model, not DFT. I have never seen a case where changing the interaction range is needed, or a good idea.

Offline zhangguangping

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Re: Back Engine Exception : Diagonalization error
« Reply #4 on: April 24, 2016, 11:26 »
This error is in 99.99% of all cases caused by atoms overlapping. Besides, the other case is only for the extended Huckel model, not DFT. I have never seen a case where changing the interaction range is needed, or a good idea.

Dear Anders,

Thanks for your reminding.

With best regards,

Guangping