Dear Colleagues,
I want to calculate the Electronic structure distribution and the structure of Simple molecules like H2 , H2O and NH3.
I want to calculate by first principle approach.
Please suggest me which process should I use for this.
Thanks and Regards
N Das
Dear Colleagues, Can I use finite difference method ?
Is it feasible ?
Thanks and Regards
N Das
Dear An-Giang Nguyen,
Thank you for your suggestion.
But, Quantum Espresso is not , I think , first principle method.
Quantum Espresso is not, I think, that much visualising for PG Students.
I may be wrong.
Thanks
N Das
Dear @Ahmad A. Al Rababah,
Thanks for your interest.
Best Wishes
N Das
By first principles approach, sir you can do study with popular software Quantum espresso, ELK or Siesta etc.
These are free and open source software.
Quantum Espresso is a free suite of first-principles materials modelling programs. It uses density functional theory (DFT) to compute the electronic structure. However, I do not think that will be the best choice for your task. Quantum Espresso, like the CASTEP program that I develop, is designed for materials and assumes that your system has 3D periodicity. Your systems are all simple molecules, so unless you're interested in the molecular crystals then neither QE nor CASTEP are likely to be the most efficient way to model them.
I suggest you look at one of the many quantum chemistry packages available for free academic use which use a local basis set (e.g. Gaussians or numerical orbitals) -- for example, Orca (https://orcaforum.kofo.mpg.de/app.php/portal).
Respected Philip James Hadnip,
Thanks a lot for nice guide.
I am happy to get the proper way .
Regards
N Das
One of best freely available codes aiming for calculate molecular systems is ORCA, it is very easy-to-use. I have recorded a video tutorial for illustrating how to use ORCA to conduct some common calculation: "Study geometry, vibration, IR spectrum and orbitals based on ORCA program and other codes" (https://youtu.be/tiTmTbtbtig).
After finishing geometry optimization by ORCA, you can convert the resulting .gbw file to .molden file via orca_2mkl tool in the ORCA package, then the .molden file can be used as input file of Multiwfn (http://sobereva.com/multiwfn) to characterize electronic structure of the molecule in a wide variety of ways, such as population analysis, bond order analysis, orbital composition analysis, electrostatic potential analysis, plotting electron density and electron localization function, drawing density difference map to show charge transfer and polarization due to forming bonds, etc.
Also check https://www.sciencedirect.com/topics/materials-science/electronic-structure-calculation
One more software that is helpfull for visualization of structures of molecule or atom is VESTA. Very helpfull for DFT calculation.
Dear Prof. Dr. Nityananda Das,
As my experience in computational chemistry. You should use GaussView software to model and Gaussian software to calculate through some keywords. Density Functional Theory (DFT) is suitable in your case.
Reference:
https://gaussian.com/
Best regards.
Some software of quantum mechanics such as Gaussian, Hyperchem, or Gamess could support you to solve it.
I absolutely agree with Dr Dang T. Nguyen suggestions, the cited softwares are the best.
Best wishes
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