From owner-chemistry@ccl.net Tue Dec 22 09:52:01 2009 From: "Thomas Exner texner.:.gmx.net" To: CCL Subject: CCL:G: GIAO and second deviations Message-Id: <-40953-091222043755-22780-4QDIMzy0U5mzk0ei7W94hQ],[server.ccl.net> X-Original-From: Thomas Exner Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-15 Date: Tue, 22 Dec 2009 10:37:48 +0100 MIME-Version: 1.0 Sent to CCL by: Thomas Exner [texner{:}gmx.net] Dear Jerome, thank you for your help. Unfortunately, this cannot be the reason. First, I did not specify the SPINSPIN keyword. Second, this keyword is even not available for MP2 calculations. Merry Christmas Thomas Jerome Kieffer schrieb: > On Mon, 21 Dec 2009 21:01:34 +0100 > "Thomas Exner texner-,-gmx.net" wrote: > >> I would like to ask a question about NMR chemical shift calculations >> based GIAO method: I use g03 to calculate the chemical shifts of a >> metal complex at the MP2 level. Because of the size of the complex >> this is very time consuming as well as demanding of scratch space. >> But when I followed the output, I noticed that the chemical shifts >> are output relatively early. But then a huge amount of computer time >> is used in link l1112.exe. If I understand it correctly, this link is >> calculating the second deviations of the energy. Are these second >> deviations really necessary? And if not, how can I circumvent their >> calculations? > > They are used for calculating coupling constants ... if you requested > the SpinSpin option with NMR. > > Merry Christmas From owner-chemistry@ccl.net Tue Dec 22 10:28:01 2009 From: "Zhong-Yun Ma mzhy1019^^^sina.com" To: CCL Subject: CCL: Isolated molecules & unoccupied orbitals: does the basis set matter? Message-Id: <-40954-091222022401-29185-5QLesAwJ6EbfDqGYACnAqA ~ server.ccl.net> X-Original-From: "Zhong-Yun Ma" Date: Tue, 22 Dec 2009 02:23:57 -0500 Sent to CCL by: "Zhong-Yun Ma" [mzhy1019++sina.com] When comparing the DOS of isolated molecules as obtained by VASP with the results of other codes which use local basis sets (Siesta, Turbomole), it seems that the states match only up to a certain energy below the vacuum energy. For higher energies (but still below the vacuum energy), neither the number nor the position of the orbitals match necessarily. I focused on the molecule 4-Pyridin-4-yl-phenylamine. Using parameters as comparable as possible, I see 4 unoccupied states below the vacuum energy with Siesta and Turbomole (at approximately the same energies). Using VASP, the DOS matches those results very nicely up to the LUMO+2. 3D-representations of the orbitals are consistent as well. Between the states LUMO+2 and LUMO+3 (according to Siesta and Turbomole), VASP calculates an additional state. By looking at its 3d-representation I can see that this state looks like what is the LUMO+4 (the first state above the vacuum energy) in siesta and turbomole. A very quick test with another plane-wave code, abinit, finds a DOS very similar to what VASP finds. To sum up, in this example I see HOMO LUMO L+1 L+2 L+3 VacEn. L+4 in siesta and turbomole. Vasp finds: HOMO LUMO L+1 L+2 ex L+3 VacEn. where the peak "ex" corresponds to L+4 from siesta and turbomole, and VacEn is the vacuum energy. From 3d representations of the L+3 state I don't think they represent the same orbital. Is it possible that plane-wave and local-basis set codes behave somehow differently concerning unoccupied orbitals? If so, why? There is a related thread, http://cms.mpi.univie.ac.at/vasp-forum/forum_viewtopic.php?4.6181 There, however, it seems that the calculation of states above the vacuum energy was the issue (which, I guess, could in principle be solved by setting NBANDS accordingly). I want to emphasize that I see (for at least three molecules i looked at so far) a different DOS also in a certain range of unoccupied states below the vacuum energy. Thanks in advance From owner-chemistry@ccl.net Tue Dec 22 11:03:01 2009 From: "Zhong-Yun Ma mzhy1019 ~ sina.com" To: CCL Subject: CCL: Isolated molecules & unoccupied orbitals: does the basis set matter? Message-Id: <-40955-091222081938-6775-ZaKYCAjQnZRPW0BhTZ6iSA++server.ccl.net> X-Original-From: "Zhong-Yun Ma" Date: Tue, 22 Dec 2009 08:19:33 -0500 Sent to CCL by: "Zhong-Yun Ma" [mzhy1019#,#sina.com] When comparing the DOS of isolated molecules as obtained by VASP with the results of other codes which use local basis sets (Siesta, Turbomole), it seems that the states match only up to a certain energy below the vacuum energy. For higher energies (but still below the vacuum energy), neither the number nor the position of the orbitals match necessarily. I focused on the molecule 4-Pyridin-4-yl-phenylamine. Using parameters as comparable as possible, I see 4 unoccupied states below the vacuum energy with Siesta and Turbomole (at approximately the same energies). Using VASP, the DOS matches those results very nicely up to the LUMO+2. 3D-representations of the orbitals are consistent as well. Between the states LUMO+2 and LUMO+3 (according to Siesta and Turbomole), VASP calculates an additional state. By looking at its 3d-representation I can see that this state looks like what is the LUMO+4 (the first state above the vacuum energy) in siesta and turbomole. A very quick test with another plane-wave code, abinit, finds a DOS very similar to what VASP finds. To sum up, in this example I see HOMO LUMO L+1 L+2 L+3 VacEn. L+4 in siesta and turbomole. Vasp finds: HOMO LUMO L+1 L+2 ex L+3 VacEn. where the peak "ex" corresponds to L+4 from siesta and turbomole, and VacEn is the vacuum energy. From 3d representations of the L+3 state I don't think they represent the same orbital. Is it possible that plane-wave and local-basis set codes behave somehow differently concerning unoccupied orbitals? If so, why? Thanks in advance! From owner-chemistry@ccl.net Tue Dec 22 14:06:01 2009 From: "Ana Montero analilian.montero*gmail.com" To: CCL Subject: CCL: software to visualize MOs Message-Id: <-40956-091222140151-4066-T6LRId/j8ATa682wA+PshA-,-server.ccl.net> X-Original-From: "Ana Montero" Date: Tue, 22 Dec 2009 14:01:48 -0500 Sent to CCL by: "Ana Montero" [analilian.montero/a\gmail.com] Hi members, I want to visualize molecular orbitals (MO) from one matrix of Atomic Orbital (AO) coefficients. Can you suggest me some software to do it? Thanks in advance ana