CCL:G: van der Waals parameters for Ti

 Sent to CCL by: "Lukasz Cwiklik" [cwiklik[]gmail.com]
 Dear Saurabh,
 I do not know any tutorial, however, I will try to describe the
 general procedure.
 The way to estimate vdW parameters with ab initio (eg. Gaussian) is to
 scan a potential energy surface for interactions between your atom
 (rutile) and the atoms/molecules which rutile will interact with in
 your simulation. In the simples case, if you have just rutile-rutile
 interactions, make a scan of energy in Gaussian  for changing the
 rutile-rutile distance. Then assume the parameters for rutile (for
 starters, take radius and  well depth for a similar atom) and make the
 same scan in your MD code. Then the hard part starts - you need to fit
 (just by hand or write a code) the radius and  well depth to have an
 agreement between ab initio and the empirical energy vs. distance
 curve (in a range of method's error which sometimes can be as high as
 2 kcal/mol).
 One should remember about the basis set superposition error, however,
 there is no ideal method to get rid of bsse in this case.
 Best,
 Lukasz
 --
 Lukasz Cwiklik
 http://cwiklik.wordpress.com
 On Mon, Nov 24, 2008 at 4:02 PM, Saurabh Agrawal
 Saurabh.Agrawal^^ucdconnect.ie <owner-chemistry===ccl.net> wrote:
 >
 > Sent to CCL by: "Saurabh  Agrawal"
 [Saurabh.Agrawal/./ucdconnect.ie]
 > Dear CCl users,
 >
 > I am trying to get non bonded parameters (van der Waals' radius and  well
 depth) for Ti atom (rutile). I appreciate if some one could provide these
 parameters to me or let me know the way (tutorial) to calculate these parameters
 using Gaussian.
 >
 > Thanking you in advance.
 >
 > Best,
 >
 > Saurabh Agrawal,
 > PhD student,
 > University College Dublin,
 > Ireland>
 >
 >