Triplet optimization of water and calculation of ZFS on it

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s.das
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Triplet optimization of water and calculation of ZFS on it

Post by s.das » 29 Jun 2015, 05:51

Hi,

I am trying to do triplet state optimization of water molecule and then calculate ZFS on it.
I think there might be problem regarding symmetry specification as I have wrote in .dal file as:
*SCF INPUT
.DOUBLY OCCUPIED
3 0 1 0
.SINGLY OCCUPIED
1 1 0 0

I am not sure if this is the correct way to specify symmetry in triplet state. I could not find any clue in the manual.
I am attaching the corresponding files.

Can anybody help me out?
Attachments
h2o-zfs-dft_1.out
(113.27 KiB) Downloaded 262 times
h2o-zfs-dft_1.mol
(280 Bytes) Downloaded 251 times
h2o-zfs-dft_1.dal
(169 Bytes) Downloaded 280 times

taylor
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Re: Triplet optimization of water and calculation of ZFS on

Post by taylor » 29 Jun 2015, 07:40

I should have perhaps been more clear when I talked about symmetry, although this is discussed in considerable detail in the manual, and also on a "sticky" posting at the top of the forum. But your problem now is that if you tell Dalton you have C2v symmetry, you must (a) ensure that your geometry input can generate this symmetry, and (b) input only atoms that are unique within this point group.

So for H2O (and your choice of X and Y for the generators is indeed the conventional one) you should put the O on the z-axis, and one H at a point that has coordinates

Code: Select all

x.xxx   0.0   z.zzz
where the actual coordinates will be determined by your starting geometry. The program will then automatically generate the second hydrogen at the point

Code: Select all

-x.xxx  0.0   z.zzz
Your current input causes the program to generate three hydrogen atoms (I think this is pretty obvious from the output!) because you have put a hydrogen on the z-axis, and then a second hydrogen off it, and the symmetry generates another hydrogen as a result. Only specify symmetry-distinct atoms when you invoke symmetry directly, and those unique atoms should be positioned according to the symmetry you specify.

Further, run your .OPTIMIZE calculation (and perhaps run a vibrational analysis at the end to verify you have a minimum), and then once you have your optimized geometry, run your response calculation for ZFS.

Best regards
Pete
P.S. If you want the 3B1 state of H2O, then your specification looks correct to me.

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