Engineering topics

Cohen, Morrel H.

Publications and source records attributed to Cohen, Morrel H..

3 records

DOE OSTI2019

Charles Kittel

We discuss solid-state physicist Charles Kittel, a professor emeritus at the University of California, Berkeley, passed away peacefully at his home in Berkeley on 15 May 2019, two months before his 103rd birthday. Born in New York City on 18 July 1916, Charlie entered MIT in 1934. He moved to Cambridge University in 1936 and received his BA there two years later. He earned his PhD degree in 1941 from the University of Wisconsin–Madison, where his adviser was Gregory Breit. From 1940 to 1942, Charlie worked on problems in degaussing and magnetic mine warfare at the Naval Ordnance Laboratory. He served in the US Navy as a research physicist at a British Admiralty research establishment in Scotland and as a naval attaché at the US Embassy in London; he went on to work on antisubmarine warfare and operations research in Washington, DC, and London. In 1945 he returned to MIT, taking a position in the Research Laboratory of Electronics.

99 GENERAL AND MISCELLANEOUS↗

DOE OSTI2018

Occupation probabilities as variables in electronic structure theory: cooper pairing, OP-NSOFT-Cs,t, and the homogeneous electron liquid

The energy functional of a novel electronic structure theory, OP-NSOFT, has as variables the natural spin orbitals (NSO) of the trial function and their joint occupation probabilities in the search for the ground state energy. When occupancy is restricted to the spin-paired NSOs of DOCI, the resulting theory, OP-NSOFT-0, scales as M 3 , with M the size of the one-electron basis set. Accurate results were obtained for small molecules, particularly near dissociation where single reference theories like DFT are inaccurate. The homogeneous electron liquid (HEL) could serve as a test bed of OP-NSOFT for condensed systems, but OP-NSOFT-0 reduces to the Hartree–Fock approximation for the HEL. Cooper pairing is introduced instead, both singlet pairing, OP-NOFT-Cs, and fully polarized triplet pairing, OP-NSOFT-Ct. The former yields 1/3 of the diffusion-Monte-Carlo correlation energy, the latter 1/2 to 1/3 with decreasing electron density for r s values between 1 and 10. Both yield the discontinuity in the single-particle occupation number required by the Luttinger theorem. Furthermore, two-state joint occupation probabilities illustrate the importance of electron–electron small-angle scattering in establishing electron correlation in the unpolarized HEL.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2016

A well-scaling natural orbital theory

Here, we introduce an energy functional for ground-state electronic structure calculations. Its variables are the natural spin-orbitals of singlet many-body wave functions and their joint occupation probabilities deriving from controlled approximations to the two-particle density matrix that yield algebraic scaling in general, and Hartree–Fock scaling in its seniority-zero version. Results from the latter version for small molecular systems are compared with those of highly accurate quantum-chemical computations. The energies lie above full configuration interaction calculations, close to doubly occupied configuration interaction calculations. Their accuracy is considerably greater than that obtained from current density-functional theory approximations and from current functionals of the oneparticle density matrix.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗