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oxygen atom's optimized PAO similar to 6-31++G** of GTO codes
Date: 2018/02/19 14:50
Name: Reza

Hi,
I need to compare results of H2O timer cluster between GTO based codes such as ORCA/Gaussian and OPENMX. In ORCA/Gaussian everything, about basis set, is simple. I used 6-31++G** for oxygen atom (see below for its coefficients and exponents). How can I define 6-31++G** in language of optimized PAO in OPENMX? I use maximum radius cutoff for oxygen in optimized PAO.

Thanks
Reza
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Re: oxygen atom's optimized PAO similar to 6-31++G** of GTO codes ( No.1 )
Date: 2018/02/19 14:52
Name: Reza

Sorry, These are exponents and coefficients:


****
O 0
S 6 1.00
5484.6717000 0.0018311
825.2349500 0.0139501
188.0469600 0.0684451
52.9645000 0.2327143
16.8975700 0.4701930
5.7996353 0.3585209
SP 3 1.00
15.5396160 -0.1107775 0.0708743
3.5999336 -0.1480263 0.3397528
1.0137618 1.1307670 0.7271586
SP 1 1.00
0.2700058 1.0000000 1.0000000
SP 1 1.00
0.0845000 1.0000000 1.0000000
D 1 1.00
0.8000000 1.0000000
****
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Re: oxygen atom's optimized PAO similar to 6-31++G** of GTO codes ( No.2 )
Date: 2018/02/23 18:51
Name: T. Ozaki

Hi,

6-31G** may correspond to

H7.0-s2p1
O7.0-s2p2d1

and 6-31++G** may correspond to

H7.0-s2p2d1
O7.0-s3p2d1f1

while I am not sure which angular momentum is augmented by the diffuse functions ++.

Regards,

TO
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Re: oxygen atom's optimized PAO similar to 6-31++G** of GTO codes ( No.3 )
Date: 2018/04/01 00:53
Name: Reza

Hi Prof. Ozaki

In 6-31G, the valance electron should be defined by two sets of contracted GTOs. The first contracted GTO is defined by using 3 GTO, and the second contracted one is defined by 1 GTO (31G in 6-31G). Please note that the 6 in 6-31G is for core electron which is not considered in OPENMX. So, I think I should use following one for Oxygen atom:


for 6-31G: O7.0-s4p4
for 6-31G**: O7.0-s4p4d1
for 6-31++G**: O7.0-s5p5d1

+ means diffused orbitals with principal quantum number of n+1.
The first + is for oxygen, and the second one is for H atom.
* means polarized orbital with L+1.

I will thank, if you leave me any comment in this field.

Very Thanks.
Reza
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Re: oxygen atom's optimized PAO similar to 6-31++G** of GTO codes ( No.4 )
Date: 2018/04/01 07:29
Name: T. Ozaki

Hi,

Since the basis functions provided in OpenMX are defined numerically and optimized variationally,
the corresponding basis set for 6-31G should be O7.0-s2p2 rather than O7.0-s4p4.
The others should be changed accordingly.

Regards,

TO
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Re: oxygen atom's optimized PAO similar to 6-31++G** of GTO codes ( No.5 )
Date: 2018/04/02 02:08
Name: Reza

So, If I correctly understand, you mean that each contracted GTO should be replaced by only one APO. Right?
For example, 6-41G will be translated to O7.0-s2p2 similar to 6-31G, and 6-311G to O7.0-s3p3. Am I right?
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Re: oxygen atom's optimized PAO similar to 6-31++G** of GTO codes ( No.6 )
Date: 2018/04/02 08:37
Name: T. Ozaki

Hi,

The contraction means that an optimized basis orbital is expressed by a linear combination of primitive
orbitals (Gaussian functions for your case), and the contraction coefficients are pre-determined so as to
reproduce some a reference function such as atomic orbital. In OpenMX, the optimized orbitals are generated
in a similar way. An important difference between them is that one uses analytic functions, the other
numerically defined functions for the primitive basis functions. It should be noted that after the contraction
the opimized orbital returns to a single numerical table for the numerical functions, while all the primitive
functions have to be treated explicitly for the analytic functions when matrix elements are evaluated.

Regards,

TO
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