Hi teacher, outstanding freeze coordinates of your procedure are incredible, But here we also add further information (bond). Thanks for uploading this video,
Thanks for posting this video. Using modredun and the -1 method will often give different results when doing a minimization (OPT/FREQ) calculation, so they aren't equivalent. From Fernando Clemente at Gaussian: ""Opt=ModRedundant" is used to add/modify the list of redundant internal coordinates. If you then use X...F, what you are doing is adding the Cartesian coordinates of an atom to the list of redundant internal coordinates and freezing those new "internal coordinates". Although, from the point of view of a geometry optimization, this sounds equivalent to freezing Cartesian coordinates via the "-1" freeze code or via "Opt=ReadOptimize", the two approaches are not the same. The Cartesian coordinates that you include in the "ModRedundant" section are being treated as internal coordinates. So, technically, with "Opt=ModRedundant", you are not freezing the Cartesian coordinates directly, instead you are freezing internal coordinates. There isn't a way to project out the contributions from frozen internal coordinates from the Hessian, for example, which is important for the vibrational frequency analysis. As a result, in a frequency calculation done this way (Opt=ModRedundant), the frequency analysis is done with the full Hessian (3*NAtoms-6 degrees of freedom). If you want to freeze atoms in Cartesian coordinates and be able to have a frequency analysis that is done on the Hessian from the constrained potential energy surface, you need to use Opt=ReadOpt (or use the "-1" freeze code in the input specification for the atoms that you want to freeze). This will result in a Hessian with 3*NActive degrees of freedom (where NActive is the number of active atoms, i.e. those that are not frozen in Cartesian coordinates)." I hope this is useful.
@@quantumguruji Yes, I learned this lesson by using the modredundant method and the -1 method and getting different results for the same model. Thanks for making your content. I wish that others would post similar videos. I should make some videos about what I've learned and the mistakes I've made using Gaussian and VASP for the past 20 years.
pubs.aip.org/aip/jcp/article/154/22/224107/313332/Accurate-frozen-core-approximation-for-all #P B3LYP/6-31G* FChk=Chkfile Title 0 1 C 0.000000 0.000000 0.000000 H 1.089000 0.000000 0.000000 H -0.363000 1.027000 0.000000 H -0.363000 -1.027000 0.000000 FC 6 7 8 9 --blank line-- In this example, the FC keyword specifies that the core electrons of carbon (atom 6) and hydrogen (atoms 7, 8, 9) will be frozen. Adjust the atomic numbers and other parameters as needed for your specific calculation. gaussian.com/frozencore/
I have no channel if you have time to upload how to use point group geometry in different cases it's too paramount topic for us especially altering the spin of electrons.
Brother help! I want to calculate the adsorption of an organic material on a specific atom of a nanotube with adsorption locator in material studio but it errors i don’t know what I did wrong. I optimized the organic material with forcit with same setting as it said in its tutorial
