Session P27: Electronic Structure II

11:15 AM–1:51 PM, Wednesday, March 15, 2006
Baltimore Convention Center Room: 324

Sponsoring Unit: DCOMP
Chair: Anne Chaka, National Institute of Standards and Technology

Abstract ID: BAPS.2006.MAR.P27.7

Abstract: P27.00007 : Prediction of Born-Oppenheimer Interatomic Forces Using Orbital-Free Density Functional Theory with Approximate Kinetic Energy Functionals

12:27 PM–12:39 PM

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  S.B. Trickey
  V.V. Karasiev
  Frank E. Harris
    (Quantum Theory Project and Department of Physics, U. of Florida)

Rapid calculation of Born-Oppenheimer forces is essential for driving the so called quantum region of a multi-scale molecular dynamics (MD) simulation. The orbital-free (OF) DFT approach is appealing but has proven difficult to implement because of the challenge of constructing reliable orbital-free approximations to the kinetic energy functional. To be maximally useful for multi-scale simulations, an OF-KE functional must be local (i.e. one-point). In the face of these difficulties, we demonstrate that there is a way forward. By requiring only that the approximate functional deliver high-quality forces, by exploiting the ``conjointness'' hypothesis of Lee, Lee, and Parr, by enforcing a basic positivity constraint, and by parameterizing to a carefully selected, small set of molecules we are able to generate a OF-KE functional that does a good job of describing various H$_q$Si$_m$O$_n$ clusters as well as CO and H$_2$O (providing encouraging evidence of transferability).

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