Author Topic: EHT data  (Read 5505 times)

sca

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EHT data
« on: March 31, 2008, 08:28:48 pm »
Hi,

I am facing problem with eht guess when I am using ECP-18 for Ti. I am trying to use this ecp-18-mhf with TZVP basis set. Could you please tell me how do I get the data for the EHT definition of 18-e ECP for Ti. Thank you in advance!
« Last Edit: April 02, 2008, 03:22:37 pm by salai »

uwe

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Re: EHT data
« Reply #1 on: April 03, 2008, 10:26:35 am »
Hi,

there are not basis sets in the basis set library that are fitted to ECP-18, def-TZVP is an all-electron basis set, and ecp-10-mdf is the only basis set for ecp-10-mdf (relativistic Ti-ECP(MEFIT,R), Q=12, see $TURBODIR/basen/ti).

You can assign any ecp to any basis set, no matter if that is reasonable or not. In define, assign a basis set like usual. Then call

ecp "ti"

and you will be asked for the name of the ECP. This is very similar to the b "ti" command in the same define menu.

If you do not know exactly the name of the ECP, just enter

?

here, and define will search the library for ECPs of Ti. Just say

y

as soon as define shows the ECP you would like to use.

Enter

ecpl

to get a list of assigend ECPs:

Quote
ecpl

------------------------------------------------------------------------
 list of effective core potentials defined yet
------------------------------------------------------------------------
  no. | nickname
------------------------------------------------------------------------
    1 | ti ecp-18-mhf
------------------------------------------------------------------------

Warning: The extended Hückel guess will not work any more since data for that step is only available for all-electron and ECP-10 basis sets!

Regards,

Uwe
« Last Edit: April 03, 2008, 10:33:59 am by uwe »

sca

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Re: EHT data
« Reply #2 on: April 03, 2008, 06:28:33 pm »
Thanks a lot for the explanation! Here is my problem! I am trying to use the PEECM method and I have to use ECPs for few Ti atoms surrounding the QM cluster without any basis functions for the valence electrons. This means that the Ti atoms are supposed to represent +4 charge with the ECPs for inner core electrons. So, I need to use the ECP-18 without any basis functions for the valence electrons. But since the EHT definition is not available for ecp-18, I am always stuck at the eht guess! I would greatly appreciate any suggestion regarding this problem! 

christof.haettig

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Re: EHT data
« Reply #3 on: April 15, 2008, 06:13:36 pm »
The proper way to at a EHT definition is
   1. prepare the input for a SCF or DFT calculation on the isolated atom
       with this ECP (or one with the same number of electrons)  and a reasonable
      basis set using the  hcore option to generate start orbitals,  and run the calculation
      in a high symmetry group (oh or ih)
   2. copy for each quantum number (1s, 2s, 2p, ...) one orbital into the basis set library file.

If you just want any set of EHT data you can copy the data from the Ca atom into the ti file
(but don't forget to copy also the corresponding basis set).

Christof

sca

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Re: EHT data
« Reply #4 on: April 15, 2008, 06:48:05 pm »
Many thanks for the explanation! It works!