“The answer to Feynman’s 1959 question ‘What would happen if we could arrange the atoms one by one the way we want them…’ has come a step closer to reality,” said Ralph C. Merkle, Chairman of the Foresight Institute Feynman Prize Committee. “Our ability to simulate and manipulate atoms will enable us to design and build engineered molecular machinery. This coming nanotechnology revolution will transform our world and our lives for the better.”
Scuseria website at Rice University
Arxiv - Constrained-Pairing Mean-Field Theory. IV. Inclusion of corresponding pair constraints and connection to unrestricted Hartree-Fock theory
Our previously developed Constrained-Pairing Mean-Field Theory (CPMFT) is shown to map onto an Unrestricted Hartree-Fock (UHF) type method if one imposes a corresponding pair constraint to the correlation problem that forces occupation numbers to occur in pairs adding to 1. In this new version, CPMFT has all the advantages of standard independent particle models (orbitals and orbital energies, to mention a few), yet unlike UHF, it can dissociate polyatomic molecules to the correct ground-state restricted open-shell Hartree-Fock atoms or fragments.
We have developed constrained-pairing mean-field theory (CPMFT), a method capable of describing static (strong) correlation in an accurate and efficient manner. The idea behind CPMFT is to make use of the pairing correlations that occur in a quasiparticle picture to describe static correlation in molecular systems. In CPMFT, we divide the natural orbitals into core, active, and virtual blocks; each core orbital has unit occupation, each virtual orbital has zero occupation, and the active natural orbitals have fractional occupations ni, where 0 less than ni less than 1. Static correlation is introduced by allowing electron pairs to have fractional occupations within an active space.
Arxiv - ROHF Theory Made Simple
Restricted open-shell Hartree-Fock (ROHF) theory is formulated as a projected self-consistent unrestricted HF (UHF) model by mathematically constraining spin density eigenvalues. The resulting constrained UHF (CUHF) wave function is identical to that obtained from Roothaan’s effective Fock operator. Our and CUHF Fock operators are parameter-free and have canonical orbitals and orbital energies that are physically meaningful as in UHF, except for eliminating spin contamination. The present approach removes ambiguities in ROHF orbital energies and the non-uniqueness of methods that build upon them. We present benchmarks to demonstrate CUHF physical correctness and good agreement with experimental results.
The winner of the 2010 Feynman Prize for Experimental work is Masakazu Aono (MANA Center, National Institute for Materials Science, Japan) in recognition of his pioneering and continuing work, including research into the manipulation of atoms, the multiprobe STM and AFM, the atomic switch, and single-molecule-level chemical control including ultradense molecular data storage and molecular wiring; and his inspiration of an entire generation of researchers who have made their own ground-breaking contributions to nanotechnology.
If you liked this article, please give it a quick review on ycombinator or StumbleUpon. Thanks
Ocean Floor Gold and Copper
Ocean Floor Mining Company