CCL: ADF-Bond energy analysis query

 Sent to CCL by: Fedor Goumans [goumans[a]scm.com]
 Dear Sonam,
First of all, you may also send ADF questions directly to our dedicated support team (support ~~ scm.com). A good starting point for understanding energy decomposition analysis is this advanced review by von Hopffgarten and Frenking: 
 http://wires.wiley.com/WileyCDA/WiresArticle/wisId-WCMS71.html
 To answer your questions:
 - Yes, the bond energy is decomposed in those three terms.
- As ADF works with fragments, the bonding energy (and its decomposition) is between the fragments you defined (atoms by default). Depending on which bond you are interested in, you can run a single point calculation where you define the two fragments either side of the bond. In this case for (PH3)2C -if I understand correctly- you could define one PH3 fragment (which is present twice) and one C fragment. The bond energy that comes from this run is then twice the C-P bond.
- to analyze bonding energy in terms of unrestricted fragments you can use the fragoccupations keyword. You would need the lower the spherical symmetry of this C atom fragment to something like D_inf_h or D2h to introduce the differentiation between the different pi directions (sigma, pi-parallel and pi-perpendicular in your molecule. 
 http://www.scm.com/Doc/Doc2012/ADF/ADFUsersGuide/page65.html#keyscheme%20FRAGOCCUPATIONS
Our support team will follow up on this, if you could send them their your geometry.
- no you don't have to use ETS-NOCV, but it can give you additional insight in how the densities between the fragments interact and get insight in specific orbital interactions even for non-symmetric molecules, see: 
 http://www.scm.com/Products/Capabilities/ETS-NOCV.html
 Hope this helps,
 Fedor
 On 1/31/2013 1:23 PM, sonam bhatia sonamalerts^^^gmail.com wrote:
 
 Sent to CCL by: "sonam  bhatia" [sonamalerts|,|gmail.com]
 Dear all,
 I am interested in performing Bond energy analysis by use of ADF. I got
   windows version installed in our lab but I am the only one in our
 group using this software. As we purchased it recently and I am new to it
 so learning its basics. I am not quite confident in performing bond energy
 analysis by it. As I have performed Geometry optimization of Ph3=C=Ph3
 system and in .out file in bond energy decomposition section:
 E pauli repulsion
 E steric interaction
 E orbital interaction
 above mentioned values comes.
 I suppose interpretation of these values give us bond energy analysis.
 Whether I am right?
 1) But if suppose i have to do this analysis for particular no. of bonds
 like in Ph3=C=Ph3 system for P=C only so how I will specify this?
 2) Moreover have you used *occupation* keyword in adf which is used to
 specify particular electronic state to individual atom.
 3) if suppose for above system I have to give  s2, p-sigma2, p-pie0
 (perpendicular), p-pie0 (parallel) electronic configuration to carbon atom,
 then how with the help of occupation keyword I can assign this electronic
 configuration.
 4) While performing bonding analysis is it mandatory to give ETS-NOCV
 calculations?
 Please help me in this regard.>
 
 --
 Dr. T. P. M. Goumans
 Business Developer
 Scientific Computing & Modelling NV (SCM)
 Vrije Universiteit, FEW, Theoretical Chemistry
 De Boelelaan 1083
 1081 HV Amsterdam, The Netherlands
 T +31 20 598 7625
 F +31 20 598 7629
 E-mail: goumans ~~ scm.com
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