tag:blogger.com,1999:blog-6172620873343846436.post713947640001626602..comments2024-03-28T02:21:49.239-07:00Comments on NZ Nano: Simple Quantum Chemistry: Hartree-Fock in PythonJacob Martinhttp://www.blogger.com/profile/13042491185977653368noreply@blogger.comBlogger22125tag:blogger.com,1999:blog-6172620873343846436.post-42366876375876698912023-06-06T21:22:24.418-07:002023-06-06T21:22:24.418-07:00Zeta is zero in this case so it it not critical to...Zeta is zero in this case so it it not critical to include.Jacob Martinhttps://www.blogger.com/profile/13042491185977653368noreply@blogger.comtag:blogger.com,1999:blog-6172620873343846436.post-12914843736569452172023-06-01T17:11:03.343-07:002023-06-01T17:11:03.343-07:00This bug change does not change the final SCF ener...This bug change does not change the final SCF energy but it does speed up the SCF loop so thanks for finding this.Jacob Martinhttps://www.blogger.com/profile/13042491185977653368noreply@blogger.comtag:blogger.com,1999:blog-6172620873343846436.post-28550854019361392432023-06-01T14:59:46.024-07:002023-06-01T14:59:46.024-07:00Good job and nice post. A bug is found: G[i,j]=G[i...Good job and nice post. A bug is found: G[i,j]=G[i,j]+P[k,l]*(TT[i,j,k,l]-0.5*TT[i,j,k,l]), which should be G[i,j]=G[i,j]+P[k,l]*(TT[i,j,k,l]-0.5*TT[i,l,k,j])Eric Zhunoreply@blogger.comtag:blogger.com,1999:blog-6172620873343846436.post-66505500361654761872023-01-06T16:00:49.950-08:002023-01-06T16:00:49.950-08:00This turns out to be due to Szabo and Ostlund usin...This turns out to be due to Szabo and Ostlund using a different value for Zeta2. This has now been changed to match that of PySCF. Jacob Martinhttps://www.blogger.com/profile/13042491185977653368noreply@blogger.comtag:blogger.com,1999:blog-6172620873343846436.post-82940157281317000122023-01-06T07:21:16.360-08:002023-01-06T07:21:16.360-08:00This comment has been removed by the author.Jacob Martinhttps://www.blogger.com/profile/13042491185977653368noreply@blogger.comtag:blogger.com,1999:blog-6172620873343846436.post-23184671633150970092022-12-31T06:52:46.596-08:002022-12-31T06:52:46.596-08:00Very nice post. Just note that if you put the Zeta...Very nice post. Just note that if you put the Zeta for He as 1.69, then you will get E = -2.84184 a.u. This Zeta value is from https://www.basissetexchange.org. Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6172620873343846436.post-54489251891272846162020-11-06T07:27:27.004-08:002020-11-06T07:27:27.004-08:00Thanks a lot!Thanks a lot!Matteonoreply@blogger.comtag:blogger.com,1999:blog-6172620873343846436.post-31716118945468124202020-06-24T17:49:53.872-07:002020-06-24T17:49:53.872-07:00Thank you! Pls, whenever you are with your laptop,...Thank you! Pls, whenever you are with your laptop, please post the current version here! Saty safe and cheers!Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6172620873343846436.post-81399315107848296312020-06-23T20:46:28.021-07:002020-06-23T20:46:28.021-07:00Thanks!
Unfortunately, I am in lockdown in anoth...Thanks! <br /><br />Unfortunately, I am in lockdown in another country without my laptop so can't give you the version on the blog. But I did find an early version of the code in an email that I pushed to github (https://github.com/nzjakemartin/HF/blob/master/HF.ipynb). <br /><br />I will update this when I get back to my laptop.<br /><br />Thanks againJacob Martinhttps://www.blogger.com/profile/13042491185977653368noreply@blogger.comtag:blogger.com,1999:blog-6172620873343846436.post-9413817622814984282020-06-23T10:07:40.244-07:002020-06-23T10:07:40.244-07:00Hi, this is great! Can you provide the original Ju...Hi, this is great! Can you provide the original Jupyter file, so that we can play around with it? Cheers!Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6172620873343846436.post-57855202291748669042020-06-20T01:59:36.716-07:002020-06-20T01:59:36.716-07:00Very helpful. Thank you so much.Very helpful. Thank you so much.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6172620873343846436.post-46725561583427087582020-06-17T15:56:28.017-07:002020-06-17T15:56:28.017-07:00They are isoelectronic meaning they have the same ...They are isoelectronic meaning they have the same number of electrons in the same orbitals (s-orbital in this case) however the potential will be different for He and HeH+ and therefore they will have different energies. Using Gaussian 16 at the HF/cc-pVTZ level of theory I got HeH+=-2.932253 and He=-2.8611533Jacob Martinhttps://www.blogger.com/profile/13042491185977653368noreply@blogger.comtag:blogger.com,1999:blog-6172620873343846436.post-84786830862350490612020-06-17T15:43:49.573-07:002020-06-17T15:43:49.573-07:00Hello,
Thanks a lot for the great efforts. I have ...Hello,<br />Thanks a lot for the great efforts. I have a question and I wish you can help me with. According to you and to Szabo, the calculations of HF on HEH+ gives the same result of the ground state energy of He. Am I right, or there is sth I missed? <br />Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6172620873343846436.post-63172087156416707422020-02-16T20:32:50.637-08:002020-02-16T20:32:50.637-08:00Thank you for your interest. The diagonal entries ...Thank you for your interest. The diagonal entries of the one-electric kinetic energy operator T11 and T22 are the QM kinetic energy of each electron. The off-diagonal terms T12 describe the quantum mechanical effects of bonding. These terms go to zero at infinity but are non-zero with overlap due to constructive interference. I would recommend the discussion in Szabo and Ostlund textbook section 3.5.2 and the paper https://aip.scitation.org/doi/pdf/10.1063/1.4875735Jacob Martinhttps://www.blogger.com/profile/13042491185977653368noreply@blogger.comtag:blogger.com,1999:blog-6172620873343846436.post-11997595228755827062020-02-09T00:45:18.303-08:002020-02-09T00:45:18.303-08:00Hi,
Thank you for this blog.
I understand that T1...Hi,<br />Thank you for this blog.<br /><br />I understand that T11 is the kinetic energy operator for the first atom and T22 is the kinetic energy operator for the second atom. But I can't understand why are we calculating T12.<br /><br />T11 = T11 + T_int(A1[i],A1[j],0.0)*D1[i]*D1[j]<br />T12 = T12 + T_int(A1[i],A2[j],R2)*D1[i]*D2[j]<br />T22 = T22 + T_int(A2[i],A2[j],0.0)*D2[i]*D2[j]SssunnNhttps://www.blogger.com/profile/08241840185218358243noreply@blogger.comtag:blogger.com,1999:blog-6172620873343846436.post-39217686023140202432020-01-15T06:41:09.910-08:002020-01-15T06:41:09.910-08:00Thanks, Let me seeThanks, Let me seeAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-6172620873343846436.post-54999077670059725302020-01-15T06:24:02.274-08:002020-01-15T06:24:02.274-08:00I think it has to do with the algorithm used to pe...I think it has to do with the algorithm used to perform the integration. PySCF uses an advanced library for calculating the integrals see https://onlinelibrary.wiley.com/doi/full/10.1002/jcc.23981 (or preprint https://arxiv.org/pdf/1412.0649.pdf). This example, however, makes use of approximations from the 1970s to solve the integrals (see https://aip.scitation.org/doi/10.1063/1.432807), which would be expected to be less accurate. If you are able to find out anything more about this please let me know!Jacob Martinhttps://www.blogger.com/profile/13042491185977653368noreply@blogger.comtag:blogger.com,1999:blog-6172620873343846436.post-71554428707716158602020-01-15T06:00:13.240-08:002020-01-15T06:00:13.240-08:00Hi,
Thanks for your blog. It is really helpful. C...Hi, <br />Thanks for your blog. It is really helpful. Can you explain, why the Hartree-Fock explained in Modern Quantum Chemistry by Szabo and Ostlund for HeH+ does not produce the same result as PhSCF(STO-3G). For Zzabo and Ostlund algorithm, the total energy is -2.8606621637 but for PhSCF (STO-3G), it is -2.8418364990824458. What is the difference between these two and what should be changed in Zzabo and Ostlund algorithm so it can produce PhSCf result.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6172620873343846436.post-19195955258549138002019-05-02T23:42:33.162-07:002019-05-02T23:42:33.162-07:00Here you go https://www.dropbox.com/s/wtevsqcjr18g...Here you go https://www.dropbox.com/s/wtevsqcjr18gmwo/HOMOHeH%2B.zip?dl=0Jacob Martinhttps://www.blogger.com/profile/13042491185977653368noreply@blogger.comtag:blogger.com,1999:blog-6172620873343846436.post-47562577590697873282019-05-02T23:40:35.364-07:002019-05-02T23:40:35.364-07:00These are given by the matrix C[]. You can see how...These are given by the matrix C[]. You can see how I made use of these coefficients to draw the molecular orbitals plt.plot(x,C[0,0]*psi_CGF_STO3G_He+C[1,0]*psi_CGF_STO3G_H,label="Bonding")Jacob Martinhttps://www.blogger.com/profile/13042491185977653368noreply@blogger.comtag:blogger.com,1999:blog-6172620873343846436.post-49088057201576971922019-05-02T17:53:55.198-07:002019-05-02T17:53:55.198-07:00Hello, this post helps me a lot, because you let, ...Hello, this post helps me a lot, because you let, in a very clear way the corresponding calculations, thanks a lot.<br />I have a question, How do you obtain the coefficients for the Gaussian functions? <br /><br />best regardsAaron Rodriguezhttps://www.blogger.com/profile/13395902884786491402noreply@blogger.comtag:blogger.com,1999:blog-6172620873343846436.post-74639203262140738382019-04-18T12:04:33.151-07:002019-04-18T12:04:33.151-07:00Great example, thanks for sharing. To complete it,...Great example, thanks for sharing. To complete it, is there a download link available of the LUMO, HOMO and density input files?Claude Falbriardhttps://www.linkedin.com/in/claudefalbriard/noreply@blogger.com