From owner-chemistry@ccl.net Sat Jan 10 15:17:01 2015 From: "Joseph E Maxwell jaymax36#gmail.com" To: CCL Subject: CCL: Molecular dynamics for metal complexes Message-Id: <-50885-150109030303-8184-FghTnz87uRThZEpb/aHNEA/./server.ccl.net> X-Original-From: Joseph E Maxwell Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=windows-1252; format=flowed Date: Fri, 09 Jan 2015 00:02:48 -0800 MIME-Version: 1.0 Sent to CCL by: Joseph E Maxwell [jaymax36 ~ gmail.com] I think the problems may be due to - [i] The difficulty of development of parameters for the dative bonds associated with metal complexes. These bonds are really more dipolar 'bonds' with the participating atoms carrying partial charges. [ii] Furthermore, multiple configurations that are associated with coordination complexes associated with metals, may be making it more difficult to develop parameters for the 'dative' bonded structures. For example, complexes w/ coordination number 6, may be in in a regular or distorted octahedron. Octaherons are very symmetrical, six - C(2)[2 coincident w/ C(4), four - C(3) and three - C(4) axes, distortions across these produces digonal, trigonal and tetragonal distortions are possible. Remember these crystals are layer latices and not true molecules.Theoretically, hexagonal complexes with a central metal is also a possibility. Complexes w/ coordination number 5 can be triangular or square bipyramidal form and the energetic of the two tend to be identical as far as I can remember. Complexes w/ coordination number 2, 3, 4, ..., ..., 7, 8 & 9 are known. There is also considerable isomerism - possible; about 10 types have been defined.- ionization, positional, optical etc. Hopefully this gives an idea of the complexity involved. And hopefully too, someone is working on it - My hats off to them --- Joe --- On 1/7/2015 1:25 AM, Eli Lam eli421^hku.hk wrote: > Sent to CCL by: "Eli Lam" [eli421[*]hku.hk] > Dear CCLers, > > I am totally new to molecular dynamics simulations. Yet I have heard from my > seniors commenting that MD simulations is unrealistic towards transition metal > complexes especially in non-convalent interactions. May I ask about the > reasons? I would be grateful if CCLers can introduce me some materials about > the basics on MD. > > Thank you so much in advance! > Eli> > >