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Alex Granovsky
gran@classic.chem.msu.su

The logic of the code that read in ECPs is very simple.
There are pairs of names and their definitions.

E.g.

H-ECP NONE

defines symbol H-ECP having the value NONE (a special symbol).
The third important thing is the line number within the $ECP
block which defines the atom to whom the value coded by the H-ECP
(i.e. NONE) belongs. Thus strictly speaking defining H-ECP once
again is a mistake, one just need to use it repeatedly.
This seems to be too complicated way of input and it does,
and most likely it will be changed in the future.
The only reason to have a symbol - value pair is for the GEN type
ECP definitions where the symbolic name is of real use.
Note the name should not be necessary  H-ECP, it can be arbitrary
but should not be longer than 8 characters. The use of -ECP suffix
is just a convention.

An example of correct $ECP group could be:

 $ECP
C SBKJC
H NONE
O SBKJC
O
H
 $END

Hopee thsi helps.

Kind regards,
Alex


On Sun Jan 6 '13 5:20pm, Masoud Nahali wrote
--------------------------------------------
>>Hi 

>the formal $ECP section format as written in the manual is:

> $ECP
>C-ECP SBKJC
>H-ECP NONE
>O-ECP SBKJC
>O-ECP
>H-ECP NONE
> $END

>as I have checked the latest version of FF it can read the following format too !!

> $ECP
>C SBKJC
>H NONE
>O SBKJC
>O
>H NONE
> $END

>so as it seems there is really no need to add the extra "-ECP" for each atom ? If it is correct please let everybody knows about it since it makes the FF input files more simple than before. Sincerely Yours, m

>Best Wishes
>Masoud Nahali
>SUT

>