many imaginary freq for initial minimum

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kra268
Posts: 11
Joined: Fri Sep 25, 2020 3:41 pm

many imaginary freq for initial minimum

Post by kra268 »

Hello everyone!

I hope you are all doing well in these difficult times! I am trying to calculate the ZPE for the initial minimum of an elementary step. After the dymmatrix calculation, I get 23 imaginary frequencies of which most of them are near zero. I used the dymzpbar.pl script and it resulted in a zpe of 0.634 eV. The zpe of the saddle was 2.094 eV (with one img freq). This results in a very high zpe correction to the barrier of 1.46 eV which doesn't make sense. Can someone take a look at the files attached (including optimization of the initial) and let me know where I am going wrong? I highly appreciate your time on this! Thank you!
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ini_freq.tar.gz
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graeme
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Re: many imaginary freq for initial minimum

Post by graeme »

Something is not right. I don't see any obvious problems in the INCAR, but the frequencies do not make sense. I'll look into it.
Please don't use this data in any subsequent calculation - you need 3 near-zero modes at a minimum for things to make sense.
kra268
Posts: 11
Joined: Fri Sep 25, 2020 3:41 pm

Re: many imaginary freq for initial minimum

Post by kra268 »

Hello Graeme!

Hope you are doing well.
I resolved this problem by including more atoms (top two layers) from the slab in the calculation. Now I have no imaginary modes (as expected).
Thank you for your time on this!

Regards,
Keerthan.
graeme
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Re: many imaginary freq for initial minimum

Post by graeme »

fantastic!
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