Valery, Thanks for your comments. The benefits are for large systems and MD. Is the speed up for MD _only_ for large system though? I'm am doing MD on system sizes as small as 500 atoms as well as some large ones (e.g. 4000+ atoms). Thanks in advance for clarifying. <div>On 5/8/07, vweber <<a href="mailto:valer...@hotmail.com">valer...@hotmail.com </a>> wrote:<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> Hi Nichols The new OT is basically a mapping of the orthogonality constrained energy functional to an unconstrained one. The orthogonality is enforced via a refinement polynomial. The minimization gets faster and faster while the wavefunction converges. It is, in the best case (e.g. during MD), about 2.5 faster than the standard OT (for what it replaces!). It converges the SCF like the standard OT or slightly faster especially if you dont update the preconditionner. As said Juerg, you really see the difference for large systems. For example a box of 512 waters will run (total time per SCF) 20% faster and 35% for 4096 waters. The speedup is much higher if no preconditionner is used. I would appreciate any feedback. Valery On May 7, 11:19 pm, "Nichols A. Romero" <<a href="mailto:naro...@gmail.com">naro...@gmail.com</a>> wrote: > Hi, > > It would be nice if someone could comment on the advantages of the new OT > algorithm. > > Thanks, > > -- > Nichols A. Romero, Ph.D. > 1613 Denise Dr. Apt. D > Forest Hill, MD 21050 > 443-567-8328 (C) > 410-306-0709 (O)