[CP2K-user] [CP2K:10844] Bond Dissociation Energy Calculation

Krack Matthias (PSI) matthia... at psi.ch
Sun Oct 14 22:05:34 CEST 2018


Dear Aniruddha

UKS is certainly a good idea. There is also the possibility of an open shell singlet. I would check the literature concerning the choice of the functional.

Best

Matthias

Von: cp... at googlegroups.com <cp... at googlegroups.com> Im Auftrag von Aniruddha Dive
Gesendet: Sonntag, 14. Oktober 2018 01:13
An: cp2k <cp... at googlegroups.com>
Betreff: Re: [CP2K:10844] Bond Dissociation Energy Calculation

Thanks Matthais,

Does it mean that I need to use Unrestricted Kohn-Sham? Also currently I am doing a singlet calculations, should I do an triplet calculations for better results?

Is REVPBE okay or should I go ahead with B3LYP XC and BLYP pseudopotentials?

Regards,
Aniruddha M Dive

On Friday, October 12, 2018 at 12:49:40 PM UTC-7, Matthias Krack wrote:
Hi Aniruddha

It seems that you are using restricted Kohn-Sham (RKS) which constrains the state of the fragments. Consider the simple textbook case of H2. RKS allows only for the fragments H+ and H- if you pull the H atoms apart.

HTH

Matthias

Von: cp... at googlegroups.com<javascript:> <cp... at googlegroups.com<javascript:>> Im Auftrag von Aniruddha Dive
Gesendet: Freitag, 12. Oktober 2018 20:19
An: cp2k <cp... at googlegroups.com<javascript:>>
Betreff: [CP2K:10842] Bond Dissociation Energy Calculation

Hi All,

I am trying to calculate the bond dissociation energy of Si-S bond using CP2K. Please find attached my input file for the same.

I am initially performing a geometry optimization of a SiH3-SH molecule to calculate the equilibrium Si-S bond length. Once I have the equilibrium bond length, I am varying the Si-S distance from 1.5 A to 7.5 A. I rerun geometry optimization for these different structures keeping the Si and S atoms fixed while allowing the other H atoms to relax.

Kindly let me know if this input files and approach looks good. I am getting the bond dissociation energy to be 100 kcal/mol whereas the literature value is ~ 145 kcal/mol

Regards,
Aniruddha M Dive
Phd Candidate
Washington State University
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