Emergence of half-metallicity in suspended NiO chains: Ab initio electronic structure and quantum transport calculations

Contrary to the antiferromagnetic and insulating character of bulk NiO, one-dimensional chains of this material can become half metallic due to the lower coordination of their atoms. Here we present ab initio electronic structure and quantum transport calculations of ideal infinitely long NiO chains and of more realistic short ones suspended between Ni electrodes. While infinite chains are insulating, short suspended chains are half-metallic minority-spin conductors that displays very large magnetoresistance and a spin-valve behavior controlled by a single atom.

Improvements in DFT Calculations of Spin–Spin Coupling Constants

Different types of spin–spin coupling constants (SSCCs) for several representative small molecules are evaluated and analyzed using a combination of 10 exchange functionals with 12 correlation functionals. For comparison, calculations performed using MCSCF, SOPPA, other common DFT methods, and also experimental data are considered. A detailed study of the percentage of Hartree–Fock exchange energy in SSCCs and in its four contributions is carried out. From the above analysis, a combined functional formed with local Slater (34%), Hartree–Fock exchange (66%), and P86 correlation functional (S66P86) is proposed in this paper. The accuracy of the values obtained with this hybrid functional (mean absolute deviation of 4.5 Hz) is similar to that of the SOPPA method (mean absolute deviation of 4.6 Hz).

Cleavage of the C–C Bond in the Ethanol Oxidation Reaction on Platinum. Insight from Experiments and Calculations

Using a combination of experimental and computational methods, mainly FTIR and DFT calculations, new insights are provided here in order to better understand the cleavage of the C–C bond taking place during the complete oxidation of ethanol on platinum stepped surfaces. First, new experimental results pointing out that platinum stepped surfaces having (111) terraces promote the C–C bond breaking are presented. Second, it is computationally shown that the special adsorption properties of the atoms in the step are able to promote the C–C scission, provided that no other adsorbed species are present on the step, which is in agreement with the experimental results. In comparison with the (111) terrace, the cleavage of the C–C bond on the step has a significantly lower activation energy, which would provide an explanation for the observed experimental results. Finally, reactivity differences under acidic and alkaline conditions are discussed using the new experimental and theoretical evidence.

VII. Calculations, [1794]

One sheet of paper arranged by columns for the years 1792, 1793, 1794 with currency amounts and final sums below. "Papers & notes of Thomas Adams" written on verso.

Calculations of stone work in new dining halls and chapel, [ca. 1814]

Estimate for $10,189.62 to complete stone work in University Hall. This includes the front basement, end basement, window stools, door ports, and stairs.

[Salary and Treasury calculations and accounts], 1801

Three leaves with handwritten calculations and account information related to faculty salaries, the assignments on delinquents, rents, and repairs. One leaf is inscribed "R. Hallowell Feb. 28 1801" and likely refers to Robert Hallowell (later Gardiner), a member of the Harvard Class of 1801.

[Repairs and occasional expenses calculations, 1801]

Slip of paper with calculations for unidentified "repairs" and "occasional expenses" between 1796 and 1801.

VII. Calculations, [1794]

One sheet of paper arranged by columns for the years 1792, 1793, 1794 with currency amounts and final sums below. "Papers & notes of Thomas Adams" written on verso.