Actually i am so new to this field i am using chem craft for optimization.But i couldn't find proper way to optimize even for the small reactions. After processing completed ,i am getting wrong optimization only...So i want to know that is there any online tutorial or some other materials which can explain regarding this? ..I want to know how to determine proper bond angle and dihedral angle for given molecules and how to determine at what distance should i keep the given molecules to get correct optimization
Hai hongguang I have referred gauss view ..really it is much more better than chem craft....but the only problem is it is little difficult to use..So I am going to refer gauss view help content fully...If thr is any link please send me....
Dear Radhika
If you are not familiar with gaussview, you can use chem3D and chemdraw programs
You can draw the 2D molecular structure with chemdraws, then read this file into
chem3D. It will automatically convert molecular structure to 3D type.
Next, you can save 3D structure with .xyz. etc. Finally, you can get the molecular
structure with cartesian cooridinate
But I also recommend you to get familiar with gaussview!
Thank u so much both of u........I try to get familiar with gaussview....
Dear friend
For optimizing, you can use the command e.g., B3LYP 3-21G Opt test.
You should note that:
1-B3LYP means you chose DFT method and B3LYP as its functional. If you use HF and UHF means you chose Hartree-Fock and Unrestricted Hatree-Fock method.
2-The 3-21G is basis functions.The basis functions are suitable for carbon-based systems. But you shold choose appropriate basis functions based on own molecule.
3- Opt test is command for doing optimization process.
Best Regrads
Thanks Shubhankar your link is very useful...And I will surely go through that book..
Dear Sir
For optimizing a molecule and find its bond length, bond angle and dihedral angle, you should use the command '#B3LYP 3-21G Opt test". B3LYP means you want to use DFT method and B3LYP as its functional. If you want to use Hartree-Foc or Unrestricted Hartree-Fock, you should use HF and UHF, respectively. 3-21G are basis functions. It is suitable for carbon based clusters. If some of the elements of molecule belong to 4th raw and higher than 4th raw of perodic table you should use LANL2DZ basis functions. Please not ethat you should use suitable basis function. Opt test is the command of optimization. In file.out of Gaussian you can see the information you want.
Best Regards
How to optimize two molecules in Gaussian 09w to know the interactions between them.
I found this channel very helpful.
https://www.youtube.com/channel/UC93NlZ2s-jqMGpeuAlXlSkQ
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