Basis Sets part 2

We discuss several popular basis sets, and briefly discuss how the basis set size affects the quality of quantum chemistry computations

[@mevansthechemist]

16:04 A lot of memories on this slide for me. As a graduate student, I met Thom Dunning at Illinois. Before that, I did some calculations using aug-cc-PVDZ (having NO idea what that meant!) as an undergraduate studying silenes in supersonic cooled jets. Never got to connect the dots!

[@HetrryParx]

amazing

[@ayanbhowmick5427]

I was trying to HF-SCF code for H2O using python but wasn't able to understand basis and how to use it. After watching this video , I'm confident.

[@expeditadjovi9927]

good job, I'm not verry good in English🤣🤣🤣🤣🤣🤣 but I try to understand and all thing understanble....great

[@Learning432]

Dear Prof., hi. You are working nicely and enthusiastically. Make a video explaining how to choose the appropriate hybrid functional & basis set for specific transition metals for inorganic clusters like [XM12O40]n-, Polyoxometalates (POMs) are clusters of units of oxoanions of transition metals, such as Mo, W, V and Nb.

[@mardocheetchoumbou6264]

Hi Professor David! Between 07:28 - 09:42, please could you help to more understand the anatomy of basis set C atom, 6-31G ?

[@karenjeandiez6331]

I dunno if I get this right... but when dealing with anions is it preferable to use lower zetas like double or triple? or is it okay to use higher zetas given that high diffusion and high polarizability are indicated in the basis set?

[@biggiantmagneticfield11]

@David Sherrill At 5:02, did you mean that those are the coefficients and not the exponents for the 2p? I just want to be sure.

[@DavidSherrill1]

oops yeah, I meant coefficients there

[@lingjiang8276]

Hi David! At 20:20, the slide of "Dunning’s Correlation-Consistent Basis Sets", the 4th bullet point, cc-pVTZ would be 4s3p2d1f. I'm wondering why it's not 4s3p1d. And you mentioned about the shell idea. Would you please explain more about this? Thanks!

[@DavidSherrill1]

When you go up in the zeta-level (say, from DZ to TZ), you also add one higher angular momentum to the basis. So, cc-pVDZ goes up to d functions (for an element like carbon), and therefore cc-pVTZ goes up to f functions. And cc-pVQZ would go up to g functions. Dunning's study found that adding a set of f functions to the basis in cc-pVTZ was approximately as important as adding that 4th s function, or the 3rd set of p functions, or the 2nd set of d functions. That's what I meant about adding functions in "shells"

[@lingjiang8276]

@@DavidSherrill1 Thank you very much, David! I have learnt a lot from your lectures!

[@pouyanosratkhah4235]

In the previous video "basis sets part 1" you said that a carbon atom will have 5 basis functions (1s , 2s, 2px , 2py , 2pz) (a distinct function for every angular momentum of p orbital) but in this video , in the anatomy of basis set for carbon atom (STO-3G) there is only 3 set of functions (3 set of coefficients). Am I have the wrong point of view ? or these sets ignore different functions for different angular momentums?

[@DavidSherrill1]

All correct... you only need 3 sets of coefficients, because the p_x, p_y, and p_z functions have identical coefficients, they just point in different directions

[@DavidSherrill1]

So, one set of coefficients for 1s, one set of 2s, and one set for {2p_x, 2p_y, and 2p_z}