From owner-chemistry@ccl.net Wed Nov 28 08:53:01 2007 From: "feng zhu zhufengcc{:}gmail.com" To: CCL Subject: CCL: spin changes through the reaction Message-Id: <-35730-071128053054-12155-pqxmSJ58Cedb6Fdd/bIJ6w*server.ccl.net> X-Original-From: "feng zhu" Date: Wed, 28 Nov 2007 05:30:51 -0500 Sent to CCL by: "feng zhu" [zhufengcc * gmail.com] Dear All, I want to know how to deal with the spin-cross in the reaction path. For example, a reaction from A to B: For A, spin=1 is the most stable state while spin=3 is excited state. But for B, spin=3 is the most stable state and spin=1 is excited state. Then how we calculate this reaction path, how we define the barriar of this reaction, and how we estimate the possibility of this reaction? Thank you very much! Zhu From owner-chemistry@ccl.net Wed Nov 28 10:50:02 2007 From: "Mike Towler mdt26..cam.ac.uk" To: CCL Subject: CCL: Quantum Monte Carlo workshop, Tuscany Message-Id: <-35731-071128093409-32688-w0OTmlK8tzb5w6a91DEmag[a]server.ccl.net> X-Original-From: "Mike Towler" Date: Wed, 28 Nov 2007 09:34:06 -0500 Sent to CCL by: "Mike Towler" [mdt26]_[cam.ac.uk] WORKSHOP ANNOUNCEMENT "Quantum Monte Carlo in the Apuan Alps IV" ========================================== Sat 26th July - Sat 2nd August 2008 The Towler Institute, via del Collegio, Vallico Sotto, Tuscany, Italy http://www.vallico.net/tti/tti.html (Click 'PUBLIC EVENTS') A4 POSTER FOR THE WORKSHOP AVAILABLE HERE : http://www.vallico.net/tti/qmcitaa_08/poster.png Continuing the series of alternative and very informal meetings at this venue, the Cambridge University Theory of Condensed Matter group is organizing a fourth International Workshop to discuss the development and application of the continuum quantum Monte Carlo method in condensed matter physics and quantum chemistry. The conference will take place in a 16th Century monastery in the mediaeval high mountain village of Vallico Sotto (in the Tuscan Apuan Alps near the beautiful Italian city of Lucca). The normal format for these events involves formal presentations being restricted to the mornings, with the afternoons left free for relaxed discussion and participation in fun activities. For the young and vigorous, we organize mountain walks, caving and other healthy outdoor exercise, whilst the unfit and elderly might enjoy artistic tours, city visits and spa treatments, with all participants reuniting in the evening for excellent Tuscan dinners in local restaurants. The monastery is a unique venue where the community spirit and magnificent location have inspired memorable meetings in the past. This year's workshop will involve up to 35 people, all accommodated on site. Given the limited space most speakers will be specifically invited, but anyone who feels that they have something to contribute and who wishes to attend the event is most welcome to contact the organizers (Mike Towler: mdt26 at cam.ac.uk) for further details. There is no charge either for attendance at the conference or accommodation. CONFIRMED SPEAKERS: David Ceperley (University of Illinois), Neil Drummond (Cambridge University), Matthew Foulkes (Imperial College, London), Pablo Lopez Rios (Cambridge University), Lubos Mitas (University of North Carolina), Andrew Morris (Cambridge University), Richard Needs (Cambridge University), Norbert Nemec (University of Regensburg), Mike Towler (Cambridge University), John Trail (Cambridge University) FURTHER DETAILS AND PHOTOS FROM PREVIOUS WORKSHOPS ACCESSIBLE ON TTI WEB PAGE - CLICK THE 'PUBLIC EVENTS' LINK OR LOOK AT 'EVENT PHOTOS'. TTI CURRENTLY TAKING BOOKINGS FOR THE HOSTING OF CONFERENCES, SCHOOLS AND GROUP MEETINGS IN EASTER/SUMMER 2008. ENQUIRIES WELCOME. From owner-chemistry@ccl.net Wed Nov 28 13:08:01 2007 From: "Mike Towler mdt26(a)cam.ac.uk" To: CCL Subject: CCL: QMC summer school - Tuscany Message-Id: <-35732-071128130531-16754-LIETkAKMO7sozTBpRHrZTQ|,|server.ccl.net> X-Original-From: "Mike Towler" Date: Wed, 28 Nov 2007 13:05:27 -0500 Sent to CCL by: "Mike Towler" [mdt26_._cam.ac.uk] SUMMER SCHOOL ANNOUNCEMENT "Quantum Monte Carlo and the CASINO program III" ================================================ Sun 3rd August - Sun 10th August 2008 The Towler Institute, via del Collegio, Vallico Sotto, Tuscany, Italy http://www.vallico.net/tti/tti.html (Click 'PUBLIC EVENTS') A4 POSTER FOR THE SCHOOL AVAILABLE HERE: http://www.vallico.net/tti/qmcatcp_08/poster.jpg The third international summer school in the series "Quantum Monte Carlo and the CASINO program" will take place during August 2008 at the Towler Institute monastery in the Tuscan Apuan Alps, organized and hosted by members of Cambridge University physics department's Theory of Condensed Matter (TCM) Group. The aim of the school is to give students a thorough introduction to quantum Monte Carlo as a method for performing high-quality calculations of the electronic structure of real materials. The course is designed for young scientists who have no previous experience with this technique, though anyone interested is welcome to take part. Describing the complex behaviour of materials at the atomic level requires a sophisticated description of the correlated motion of the electrons. Quantum Monte Carlo (QMC) is an increasingly popular and explicitly many-body method with the unusual capability of yielding highly accurate results whilst also exhibiting a very favourable scaling of computational cost with system size. Over the last seventeen years, the Cambridge group have been researching QMC methods and we have created a powerful, general computer program - CASINO - to carry out the calculations. The school will focus both on the basic theory of QMC and on more advanced practical techniques, and will include a thorough introduction to the CASINO program. A background in density functional theory or similar is normally thought to be useful. The monastery is a delightful 16th century building incorporating an ancient church, and is situated in the isolated but spectacular setting of the Tuscan mountain village of Vallico Sotto. It is fully equipped with state of the art presentation and computer technology. All accommodation is on-site. There is a strictly-enforced policy for all events at the Institute that considerable time should be set aside for mountain hikes, caving, canyon walking, swimming in thermal baths, eating in wonderful local restaurants, visits to classical concerts in Lucca and Barga, and similar activities. Instructors will include the main authors of the CASINO program, (Prof. Richard Needs, Dr. Mike Towler, Dr. Neil Drummond, and Dr. Pablo Lopez Rios) and possibly others. The cost of the school for one week including accommodation will be around 400 GBP. Participants would need to arrange a flight to Pisa airport from where onward transportation will be arranged. Interested students should contact Mike Towler (mdt26 at cam.ac.uk) for registration and further details. Nice emails from students attending previous schools in this series: -------------------------------------------------------------------- "Just a brief note to thank you again for hosting the QMC summer school. I had a wonderful time in Tuscany, it was probably the best conference or school I've attended. The science was excellent, and the location, obviously, stunning. The Towler Institute is a very impressive place. Every one of the participants was a pleasure to spend time with, and I've come away with some friends with whom I intend to keep in contact." "I am really happy to see that you are preparing a new Casino Summer School in Vallico Sotto. It remains for me the most profitable workshop I have ever had, associating the top quality of lectures and the excellent practical training, making very difficult things to become accessible. It remains also for me the type of ideal ambience associating work, scientific discussion and entertainments." "You bet how wonderful time I had (I believe others students did too) in this fantastic summer school!! I would like to quote a very popular Chinese poem to show my personal feeling of the almost ideal life in Vallico Sotto. "Drinking Poem - 5 of 20" by Tao Yuan-ming I built my hut within where others live, But there is no noise of carriages and horses. You ask how this is possible: When the heart is distant, solitude comes. I pluck chrysanthemums by the eastern fence And see the distant southern mountains. The mountain air is fresh at dusk. Flying birds return in flocks. In these things there lies a great truth, But when I try to express it, I cannot find the words. This can be recited by almost every Chinese fellow. I am also grateful for the night of awesome firework, which was like special "time tunnel" to bring me back to my childhood. Thank you and thank you!! I was in a bit hurry I didn't bring camera with me, but the whole beautiful scenery has been deeply impressed in my memory, which is unfadable for sure.." "I will advice your school to anyone on the earth" DETAILS AND PHOTOS FROM LAST YEARS EVENT ACCESSIBLE ON TTI WEB PAGE - CLICK ON 'PUBLIC EVENTS' LINK OR LOOK AT 'EVENT PHOTOS'. TTI CURRENTLY TAKING BOOKINGS FOR THE HOSTING OF CONFERENCES, SCHOOLS AND GROUP MEETINGS IN EASTER/SUMMER 2008. Enquiries to mdt26 at cam.ac.uk . From owner-chemistry@ccl.net Wed Nov 28 18:00:00 2007 From: "Pratik Verma pratikv]![stanford.edu" To: CCL Subject: CCL: Projecting singlet density from broken symmetry density Message-Id: <-35733-071128175657-710-jN5yi7GMLmUaGx/NN8xBYQ{:}server.ccl.net> X-Original-From: "Pratik Verma" Date: Wed, 28 Nov 2007 17:56:54 -0500 Sent to CCL by: "Pratik Verma" [pratikv/a\stanford.edu] Hi all, I am interested in determining the ground state density of an anti-ferromagnetically coupled system. I have been looking at broken symmtery approach that allows one to use single slater determinants and hence a variety of DFT methods. Within the broken symmetry approach the open shell singlet state is approximated a single determinant by mixing the HOMO and the LUMO of the closed shell singlet state. However, the optimized broken symmtery density is a mixture of the open shell singlet density (S=0,Ms=0) and triplet density (S=1, Ms=0), neither of which can be individually described by a single slater determinant. The amount of triplet contamination can be estimated from the deviation of S**2 value > from 0 for the broken symmtery state. Since, the other two microstates (Ms=+-1) of the triplet state can be described well as single determinants, the energy of the triplet density contaminating the broken symmtery density can be computed by computing either of the the two triplet densities. Now, I am interested in projecting out the open shell singlet density from the broken symmtery density but I cannot actually compute the specific triplet state that contaminates the broken symmetry state. Is anyone aware of any approach that allows one to get the open shell singlet density from the broken symmetry density? From owner-chemistry@ccl.net Wed Nov 28 19:38:00 2007 From: "nokophala[#]aim.com" To: CCL Subject: CCL: spin changes through the reaction Message-Id: <-35734-071128192709-29461-U212J891jQQ4rfvMa3KbGQ.:.server.ccl.net> X-Original-From: nokophala_._aim.com Content-Type: multipart/alternative; boundary="--------MB_8CA0035AD4ACF4E_1AE0_6566_webmail-stg-d07.sysops.aol.com" Date: Wed, 28 Nov 2007 19:26:53 -0500 MIME-Version: 1.0 Sent to CCL by: nokophala/./aim.com ----------MB_8CA0035AD4ACF4E_1AE0_6566_webmail-stg-d07.sysops.aol.com Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii" You could calculate the reaction profile for each spin state, then identify the crossing of the two potential energy surfaces to locate the activation barrier. But a parameter that will remain unknown is the spin changing probability. Sometimes, even if activation energy is low, spin crossing can be difficult; These types of reactions are said to be spin forbidden. -----Original Message----- > From: feng zhu zhufengcc{:}gmail.com To: Phala, Noko Sent: Wed, 28 Nov 2007 4:30 am Subject: CCL: spin changes through the reaction Sent to CCL by: "feng zhu" [zhufengcc * gmail.com] Dear All, I want to know how to deal with the spin-cross in the reaction path. For example, a reaction from A to B: For A, spin=1 is the most stable state while spin=3 is excited state. But for B, spin=3 is the most stable state and spin=1 is excited state. Then how we calculate this reaction path, how we define the barriar of this reaction, and how we estimate the possibility of this reaction? Thank you very much! Zhuhttp://www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp://www.ccl.net/chemistry/sub_unsub.shtmlhttp://www.ccl.net/spammers.txt________________________________________________________________________ More new features than ever. Check out the new AIM(R) Mail ! - http://o.aolcdn.com/cdn.webmail.aol.com/mailtour/aol/en-us/text.htm?ncid=aimcmp00050000000001 ----------MB_8CA0035AD4ACF4E_1AE0_6566_webmail-stg-d07.sysops.aol.com Content-Transfer-Encoding: 7bit Content-Type: text/html; charset="us-ascii" You could calculate the reaction profile for each spin state, then identify the crossing of the two potential energy surfaces to locate the activation barrier. But a parameter that will remain unknown is the spin changing probability. Sometimes, even if activation energy is low, spin crossing can be difficult; These types of reactions are said to be spin forbidden.
-----Original Message-----
> From: feng zhu zhufengcc{:}gmail.com <owner-chemistry * ccl.net>
To: Phala, Noko <nokophala * aim.com>
Sent: Wed, 28 Nov 2007 4:30 am
Subject: CCL: spin changes through the reaction


Sent to CCL by: "feng  zhu" [zhufengcc * gmail.com]
Dear All,

I want to know how to deal with the spin-cross in the reaction path.

For example, a reaction from A to B:
For A, spin=1 is the most stable state while spin=3 is excited state.
But for B, spin=3 is the most stable state and spin=1 is excited state.

Then how we calculate this reaction path, how we define the barriar of this 
reaction, and how we estimate the possibility of this reaction?

Thank you very much!

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