You might also consider to include a basis set with relativistic correction since Iodine is quite heavy element.

Hi Marko, unfortunately I am not aware of any 6-31G(d,p) basis for iodine. I believe the 6-31G family of basis set is only defined through Zn.

For an atom like iodine, it may be most reasonable to use an ECP basis. Gaussian provides a number of them. I believe LanL2DZ has similar quality to 6-31G.

You can pick another basis set at the EMSL basis set exchange site

https://bse.pnl.gov/bse/portal

Thank you :)

You might also consider to include a basis set with relativistic correction since Iodine is quite heavy element.

Dear Marko Hanzevacki

We can able to download the Gaussian input & output files from NIST Computational Chemistry Comparison and Benchmark Database (CCCBDB). This database also provides the computed vibrational scaling factors, HOMO-LUMO band gap results and many results for computational chemists.

Gaussian input & output files download link for Iodine atom

http://cccbdb.nist.gov/iofiles2.asp

Check it out the files availability of your molecule.

http://cccbdb.nist.gov/gaufiles1.asp

You better to reference the lectures to know about the suitable basis set for Iodine atom. I agree with Mr. Xiaolei Zhu comments. I also believe LANL2DZ basis set will provide good results for you.

Format for Gaussian Keyword of DFT method

Route section: # B3LYP/6-31G(d,p)

I hope this may HELP you

check this site: https://bse.pnl.gov/bse/portal and you will find many basis sets that you can choose from..happy computing!

Dear Marko

I you had a valid answer please share correct Gaussian input files..

Thanks a lot

#p opt B3LYP/6-31+G(d,p) pseudo=read

title

0 1

C 0 2.761407 2.846655 -1.036183

C 0 2.422946 3.340287 -2.284593

C 0 1.178005 3.145743 -2.744684

C 0 0.278939 2.417878 -2.026444

C 0 -0.217767 -0.329338 0.591848

C 0 0.560663 -2.718428 1.546115

C 0 -0.160419 -1.910685 2.359681

I 0 2.478680 1.418914 1.643566

H 0 3.737620 2.974225 -0.556691

H 0 3.254214 3.814990 -2.808435

H 0 0.877932 3.306958 -3.791514

H 0 -0.450258 -2.167045 3.460679

H 0 -2.330963 1.876440 0.699286

I 0

LanL2DZ

***

H B C O 0

6-31+G(d,p)

***

Keep returning

Atomic number out of range for 6-31G basis set.  !!!

You must specify :

#p opt B3LYP/gen pseudo=read

title

0 1

C 0 2.761407 2.846655 -1.036183

C 0 2.422946 3.340287 -2.284593

C 0 1.178005 3.145743 -2.744684

C 0 0.278939 2.417878 -2.026444

C 0 -0.217767 -0.329338 0.591848

C 0 0.560663 -2.718428 1.546115

C 0 -0.160419 -1.910685 2.359681

I 0 2.478680 1.418914 1.643566

H 0 3.737620 2.974225 -0.556691

H 0 3.254214 3.814990 -2.808435

H 0 0.877932 3.306958 -3.791514

H 0 -0.450258 -2.167045 3.460679

H 0 -2.330963 1.876440 0.699286

I 0

LanL2DZ

***

H B C O 0

6-31+G(d,p)

***

I 0

LanL2DZ

Good luck!

Dear all,  Is there any other improved basis set than LanL2DZ for Iodine (53 valence electrons) as it is only having only 8 basis function? which is less than the minimal basis set.

Very helpful thread! Does anyone know if the TZP-DKH basis set is any good for a series of halogens Cl to I?

Doing some Crystal Explorer simulations and this seems the only decent basis set which covers all the halogens. Does it give meaningful and quantitative results?

DEF2TZVP is a better basis set for iodine, it treats explicitly 25 valence electrons