Molcas Forum

zz

Member

Registered: 2022-10-17

Posts: 13

[SOLVED]Identifying symmetry using z-matrix

I want to use Z-matrix input for calculation. symmetry still exists in the xyz coordinate obtained by Z-matrix transformation in log file, but molcas cannot recognize the set point group keywords. How can I use symmetry keywords while using Z-matrix input?

It's not going as follows
&GATEWAY
Title= uo2cl2 in C2V symmetry
symmetry
xy y
XBAS=ANO-RCC-VTZP
zmat
U1						
Cl2	1	2.5049656				
Cl3	1	2.5049656	2	107.795782		
O4	1	1.7488885	3	94.2185517	2	-95.8050332
O5	1	1.7488885	4	165.6565511	3	125.8881242
end of z-matrix
END OF INPUT

not setting symmetry, normal operation and output

&GATEWAY
Title= uo2cl2 in C2V symmetry
XBAS=ANO-RCC-VTZP
zmat
U1						
Cl2	1	2.5049656				
Cl3	1	2.5049656	2	107.795782		
O4	1	1.7488885	3	94.2185517	2	-95.8050332
O5	1	1.7488885	4	165.6565511	3	125.8881242
end of z-matrix
END OF INPUT
 
&SEWARD 

 &SCF &End
ITERATIONS
300
PRORbitals
2 5.0
charge
0
&GRID_IT
end of input

Last edited by zz (2022-10-27 13:20:09)

Ignacio

Administrator

From: Uppsala

Registered: 2015-11-03

Posts: 1,085

Re: [SOLVED]Identifying symmetry using z-matrix

You have to build your zmat with symmetry-unique atoms only, and make sure it complies with the symmetry requirements (i.e., atoms at symmetry axes or planes are exactly there, otherwise they'll be replicated). You may need to add dummy atoms

symmetry
xy y
zmat
U1
X       1       1.0
Cl1     1       2.5049656       2       53.897891
O2      1       1.7488885       2       97.17138        3       90.0
end of z-matrix

zz

Member

Registered: 2022-10-17

Posts: 13

Re: [SOLVED]Identifying symmetry using z-matrix

Small systems can be set manually, but for symmetric systems with more than 50 atoms, is there a program that can help me write the Z-matrix input?

zz

Member

Registered: 2022-10-17

Posts: 13

Re: [SOLVED]Identifying symmetry using z-matrix

and when do we need a ghost atom?

Ignacio

Administrator

From: Uppsala

Registered: 2015-11-03

Posts: 1,085

Re: [SOLVED]Identifying symmetry using z-matrix

The first atom will be at the origin, the 2nd in the Z axis, and the 3rd in the XZ plane. If that doesn't fit your needs  (as in this case, where we don't want any atom in the Z axis), you can use ghost atoms.

zz

Member

Registered: 2022-10-17

Posts: 13

Re: [SOLVED]Identifying symmetry using z-matrix

Such an input requires extremely high symmetry, once the atom is a little bit not on the coordinate axis or plane, the symmetry operation will be performed. Is there any keyword to relax the limit value of symmetry operation

Ignacio

Administrator

From: Uppsala

Registered: 2015-11-03

Posts: 1,085

Re: [SOLVED]Identifying symmetry using z-matrix

There's SYMTHRESHOLD, but I think it only works with XYZ input.

zz

Member

Registered: 2022-10-17

Posts: 13

Re: [SOLVED]Identifying symmetry using z-matrix

Okay, thank you very much!