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Abstract in the proceedings of ISMAR-CA'98 on page 501
Abstract in the proceedings of ISMAR-CA'98 on page 502
An illustration of divided magnetic dipoles
A depiction of benzene susceptibiliy tensor in full
Benzene susceptibility divided into 25 groups
Position coordinates/location of dipole origins
Calculated Shielding Components and Diagonalized values
The pictorial depiction of symmetry of calculated tensor orientations
Calculation at proton 1 with 24 & 25 groups
Consideration of Ethylene situation
Results and Discussion
PERSPECTIVES ON POINT DIPOLE APPROXIMATION:
The context of (intermolecular and intramolecular) NMR chemical shifts
Department of Chemistry
North Eastern Hill University
PO NEHU Campus Mawkynroh Umshing
SHILLONG 793022 Meghalaya
The simplest method by which the trends of the contributions to induced fields at a nuclear site can become sensible to a chemist is the most popular point-dipole approximation. Obviously as one begins to learn the application of the point dipole approximation in the contexts of the trends in NMR chemical shifts, it seems at the same time a beginning has been made to learn more about the limitations of this approach. Earlier1 there had been efforts to point out the approaches to contain the applications in conformity with the limitations. The recent publication2 on the Biphenyl molecule, using the HR PMR Studies in solids with the theoretical calculations on chemical shifts, seems to be revealing further the conflicts which arise (with indications to possible compromises and reconciliations) while trying to interpret the experimental results.
In this presentation, the salient general features would be enumerated. This would convince that the equations derived using the point dipole approximation justifiably prevails in all the contexts. Considerations of the point dipole approximation is the factor which can resolve conflicts either because its application is valid in a specific context or because a specific significance gets attributed when the magnetic dipole model does not explain the experimental trends convincingly.
Excerpt from Reference No:2 cited in Abstract
J.Mag.Res., 175, (2005), p 59
Column 2, count: 24th line from bottom of column
Because we use Eq.(5) together with atom and bond susceptibilities that add up to the experimentally measured molecular susceptibility tensor , we think that the intermolecular shielding contributions obtained by the quantum chemical method should be scaled such that, for large distances Rjk , they match those from Eq.(5). The optimum scale factor turns out to be S = 0.87
Comment by S.Aravamudhan: [ Reference UH ]
The result as above from these authors is an effective information to arrive at the conclusion in the closing line of the Abstract above for the CRSI meeting in July 2006. In quantum mechanical (chemical) calculations when a variety of functional forms (from the point of view of ease of computational evaluations of matrix elements) are tried out for describing the orbital used for constructing basis sets, it becomes necessary to monitor the trends of the functions at closer nuclear distances and at farther distances (at infinity). That the equation based on magnetic dipole model must be considered to examine these trends seems a natural outcome of the intuitively appealing "lumped magnetic moment" over the distributive "magnetic susceptibility" due to charge circulations. The magnetic dipole description is inadequate at closer distances and the efforts of S.Aravamudhan had been to improve the "range of closer distances [ CLICK HERE for an Illustration ]" for the validity of point dipole approximation.
At the links below find some of the earlier Communications from Ulrich Haeberlen, the Author in the reference cited above for the results of Experiment and Theory on BIPHENYL.
http://www.geocities.com/saravamudhan1944/eenc_ampere_lille.html Display page and Go To Section 4
http://www.geocities.com/inboxnehu_sa/conference_events_2006.html Display URL and Jump to EVENT-III The ICMM2006 at SLIET,Longowal,INDIA
Further, look for "mouse-over messages" by placing the mouse cursor on the images at the event ICMM2006
Communication from organizers as copied below
----- Original Message -----
From: Chemistry Conference
To: S Aravamudhan
Sent: Wednesday, July 05, 2006 1:16 AM
Subject: RE: General Body Meeting of CRSI in Chennai
Dear Dr. Aravamudhan:
Your paper has been accepted for poster preswentation and official acceptance
letter will be sent in a day or two. Looking forward to seeing you in Chennai.
With best wishes,
Dear Fellow Chemist:
Thank you for registering to participate in the meet planned for July 12-13, 2006.
The abstract(s) you have submitted have been accepted for presentation in the
above events. The complete list of presenters is posted on the website
Please look under the Technical Program weblink.
If you have requested for accommodation, the list is posted on the website
under the weblink "Accommodation"
All technical program will be held at the I.C.S.R. building in the IIT Madras
campus. The registration desk will be open at 4:00 - 7:00 p.m. on July 11th
and from 8:00 a.m. on July 12th. Please collect your conference material from the volunteers at the desk.
If you have sent in your registration fees, please collect your receipt at the
conference venue. If you have not sent in your registration fees, please do
so when you collect your conference material.
Tea, lunch and dinner will be served on both the days.
Breakfast can be had at the Institute restaurant "Tifanys" situated in the second floor
of the Mega Mess - near Sharavati Hostel.
We plan to have a cultural program in the evening of July 12th at
the Central Lecture Theater.
If you need any other information please do not hesitate to email us.
Looking forward to seeing you at Chennai,
With best regards
Annual IITM Chemistry Symposium 2006 &
The First Mid-Year Meeting of the CRSI
Department of Chemistry
Indian Institute of Technology-Madras
Chennai - 600 036
Phone : 044 - 22574200
Fax : 044 - 22574202
Email : email@example.com
----- Original Message -----|
Sent: Tuesday, August 22, 2006 2:29 PM
Subject: IITM Chemistry Conference
> Dear All:
The Photographs for the 12th July EVENT are at http://www.chem.iitm.ac.in/CRSI/photos/12thjuly/index.htm
One of the photographs from the photo-series of 12th July 2006 appears below:|
Display the page: "Chemistry Symposium 2006"
CLICK ON Technical Programme Diaplay the Programme Schedule
The Chair Person for Session II (11:00AM - 12:30PM), Dr.S.Aravamudhan is seen in Photograph above discussing with the Speaker [IL-3] Prof.R.Raghunathan, Department of Chemistry, University of Madras, Guindy campus, Chennai-600025.
The title of this Invited Lecture-3 is "A Novel Entry into Octahydropyrrolopyrroles and their N-1-C-2 fused Derivatives: via an Intramolecular 1,3-Dipolar Cycloaddition Reaction"