From owner-chemistry@ccl.net Mon Apr 16 09:30:01 2018 From: "Frank Oellien Frank.Oellien]_[abbvie.com" To: CCL Subject: CCL: 11. Int. Conference on Chemical Structures - Scientific Program Online Message-Id: <-53237-180416092757-29883-RG4R9l9ct8ALjU4UEF3lQg{=}server.ccl.net> X-Original-From: "Frank Oellien" Date: Mon, 16 Apr 2018 09:27:54 -0400 Sent to CCL by: "Frank Oellien" [Frank.Oellien|-|abbvie.com] Dear Colleagues, the scientific program of the 11. International Conference on Chemical Structures is now online: http://www.int-conf-chem-structures.org/scientific-program.html The program covers a wide range of scientific talks with different topics like Integration of Chemical Information, Structure-Activity and Structure-Property Prediction, Structure-based Drug Design and Virtual Screening, Analysis of Large Chemical Datasets and Dealing with Biological Complexity. Besides the oral presentations 2 large poster sessions will be organized on Monday and Tuesday. The conference will open on Sunday with the Mike Lynch Award keynote lecture of the CSA Trust. The scientific program comes along with a large exhibition in which 17 software vendors will present their new products and solutions in Cheminformatics and Molecular Modeling: http://www.int-conf-chem- structures.org/exhibition.html. In addition 4 conference workshops will be organized before and after the scientific program. If you are interested in participating at the ICCS 2018, please hurry up. There are only less than 15 free seats available. Best regards, Frank Oellien From owner-chemistry@ccl.net Mon Apr 16 14:53:01 2018 From: "Susi Lehtola susi.lehtola{}alumni.helsinki.fi" To: CCL Subject: CCL: Choice of multiplicity for NiO Message-Id: <-53238-180416122422-13085-XXYpgHY34NAHAtitNRpfkA-*-server.ccl.net> X-Original-From: Susi Lehtola Content-Language: en-US Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=utf-8; format=flowed Date: Mon, 16 Apr 2018 19:24:12 +0300 MIME-Version: 1.0 Sent to CCL by: Susi Lehtola [susi.lehtola||alumni.helsinki.fi] On 04/15/2018 10:54 AM, Grigoriy Zhurko reg_zhurko..chemcraftprog.com wrote: > Sent to CCL by: Grigoriy Zhurko [reg_zhurko%a%chemcraftprog.com] > Hello, I compute Ni4O4, Ni9O4 clusters and their complexes with > carbon monoxide (me research is devoted to CO absorption on NiO). > These systems can be computed in different multiplicities. Two > approaches can be used for choosing the multiplicities: 1) Compute > each multiplicity and find the one with minimal energy; 2) In the > work of Thomas Bredow, only the multiplicity 19 was chosen for Ni9O9. > He writes in his paper: The first option works in simple cases, but for transition metal compounds in general - and transition metal oxides appear to be especially nasty - getting the right energy ordering for the different spin states may be highly nontrivial. Usually DFT gets it wrong, i.e. you get different orderings with different functionals, in which case the results shouldn't be trusted. But, ab initio methods may not work very well either. In addition to significant effects due to strong correlation (for which you need something like CAS-SCF or DMRG-SCF), dynamic correlation can also play a significant part in the energy splittings between the spin states: the true spin state ordering is due to a delicate balance between static and dynamic correlation. However, your system, Ni9O9 would appear to be well outside the computational tractability of reliable ab initio methods. So, I guess most people would just go with option 1: pick a functional that (happens to) give the right spin state ordering for a closely similar system, and then pick the spin state that has the lowest energy. -- ------------------------------------------------------------------ Mr. Susi Lehtola, PhD Junior Fellow, Adjunct Professor susi.lehtola]![alumni.helsinki.fi University of Helsinki http://www.helsinki.fi/~jzlehtol Finland ------------------------------------------------------------------ Susi Lehtola, dosentti, FT tutkijatohtori susi.lehtola]![alumni.helsinki.fi Helsingin yliopisto http://www.helsinki.fi/~jzlehtol ------------------------------------------------------------------