Spin models constructed from Hadamard matrices

A spin model (for link invariants) is a square matrix W which satisfies certain axioms. For a spin model W, it is known that W ^T W ^?1 is a permutation matrix, and its order is called the index of W. Jaeger and Nomura found spin models of index?2, by modifying the construction of symmetric spin models from Hadamard matrices. The aim of this paper is to give a construction of spin models of an arbitrary even index from any Hadamard matrix. In particular, we show that our spin models of indices a power of 2 are new.     

First evidence for a new spontaneous fission decay produced in the reaction 30Si +238U

Mean lifetimes of the high spin states in the yrast band of ¹²⁶Ba were measured by using the Doppler shift attenuation method in connection with the reaction ¹¹⁶Sn (¹⁶O, 2p4n)¹²⁶Ba at a beam energy of 73 MeV. The corresponding normalized B(E2) values are obviously reduced in the vicinity of the backbending. The results are compared with the theoretical predictions based on a realistic nucleon-nucleon interaction. Received: 9 June 1997 / Revised version: 16 October 1997     

Carbon dioxide fixation by microalgae photosynthesis using actual flue gas discharged from a boiler

Applied Biochemistry and Biotechnology - To mitigate the effects of carbon dioxide discharged from a boiler in a power plant, CO2 fixation by microalgae photosynthesis was studied. For the algae...     

AB initio calculations on the hydration energies of Br− Ion

The energies of hydrated Br^? ion for coordination numbers up to 4 have been calculated with an ab inito MO method. The most favorable orientation is the ion—dipole one, in contrast to the H-bonded orientation for Cl^?(H₂O) and F^?(H₂O). The hydration energies calculated in this study are in fair agreement with those obtained by Arshadi.     

Fluorometric determination of uranium and tungsten with o-hydroxyhydroquinonephthalein in the presence of non-ionic surfactant

Complex formation between uranium or tungsten and o-hydroxyhydroquinonephthalein (Qnph) in various micellar surfactant media has been investigated fluorometrically, and determination of uranium and tungsten based on the difference between the relative fluorescence intensities of Qnph and the metal complex at 535 nm, with excitation at 400 nm in the presence of poly(vinyl) alcohol as a non-ionic surfactant. The calibration curves were linear up to 1.0 mu/ml uranium and 0.9, mu/ml tungsten. The relative standard deviations (5 replicates) were 2.6% for tungsten and 3.0% for uranium, and recovery tests gave relatively good results (97-104%).     

Ab initio molecular orbital study of structures and energetics of Si(3)H(2), Si(3)H(2) (+), and Si(3)H(2) (-)

The geometric structures, isomeric stabilities, and potential energy profiles of various isomers and transition states in Si(3)H(2) neutral, cation and anion are investigated at the coupled-cluster singles, doubles (triples) level of theory. For the geometrical survey, the basis sets used are of the Dunning's correlation consistent basis sets of triple-zeta quality (cc-pVTZ) for the neutral and cation and the Dunning's correlation consistent basis sets of double-zeta quality with diffuse functions (aug-cc-pVDZ) for the anion. For the final energy calculations, the aug-cc-pVTZ: Dunning's correlation consistent basis sets of triple-zeta quality with diffuse functions and cc-pVQZ: Dunning's correlation consistent basis sets of quadruple-zeta quality basis sets are used for the neutral and the aug-cc-pVTZ ones for the cation and anion. The global minimum neutral (I-1: (1)A(1)) has the same framework as that (cyclopropenylidene) of the C(3)H(2) molecule. Other low-lying three isomers (I-2, I-3, and I-4) are also predicted to be within 20 kJ/mol. Five transition states are optimized and their energy relationships with the isomers are clarified. The geometric structure of the global minimum cation (C-1: (2)A(1)) has the same framework as that of the neutral, but that of the anion (A-1: (2)A(')) differs very much from those of the neutral and cation. The calculated vertical and adiabatic ionization potentials from the global minimum neutral (I-1) are 7.85 and 7.77 eV, respectively. The adiabatic electron affinity of the neutral I-1 and the electron detachment energy of the global minimum anion (A-1) are predicted to be 1.21 and 1.92 eV, respectively. The two-electron three-centered bond is widely observed in the present Si(3)H(2) neutral, cation, and anion. The contour plots of their localized molecular orbitals clearly show the existence of such nonclassical chemical bonds.     

Ab initio MO calculation of hydration energies of ammonium ions and their solvation effect

The hydration energies for the NH⁺₄ and CH₃NH⁺₃ ions were calculated by an ab initio MO method. The aqueous solvation energy difference between these two ions was found to be accounted for by the interactions of the ions with a few solvent molecules.     

Ab initioMO calculations on the acidities of water and methanol,and hydrogen bond energies of the conjugate ions with a water molecule

The acidities, deprotonation energies, of water and methanol were calculated by the use of the ab initio self-consistent-field (SCF ) molecular orbital (MO ) method with electron correlation computed by the thirdorder Møller–Plesset perturbation method and configuration interaction with double excitations. Zero-point vibrational energy correction translational energy change, and the PV work term were included to evaluate the accurate acidities. The calculated acidity difference including these corrections was 7 kcal/mol, which is somewhat smaller than the experimental ones (9.5–12.5 kcal/mol) recently determined. The hydrogen bond energies of the conjugate ions (OH^? and CH₃O^?) with a water molecule were calculated to be 2.3 kcal/mol near the Hartree–Fock limit; this energy only amounts to 25% of the (total) hydration energy difference between the two negative ions. The aqueous solvation effect on the acidity scale was discussed.     

Ab initio MO study on the global minimum structure of C3H3 anion: propynl-1-yl versus allenyl anions

The geometrical structures of the C₃H⁻₃ anion are surveyed at the coupled-cluster doubles (CCD) level of theory with the aug-cc-pVDZ basis set. To clarify the CCD geometries, the stable two isomers -- propynl-l-yl 1 and allenyl 2 anions -- are further optimized at the coupled-cluster singles, doubles (triples) (CCSD(T)) level of theory both with the aug-cc-pVDZ and aug-cc-pVTZ basis sets. The final energies are calculated at the CCSD(T) and the complete active space self-consistent field (CASSCF) multi-reference internally contracted CI (MRCI) levels of theory with the aug-cc-pVTZ basis set. At the MRCI level of theory including both the corrections due to the cluster energies (MRCI+Q) and the zero-point vibrational energies, the allenyl anion 2 is about 1.3 kcal mol⁻¹ lower in energy than the propynl-l-yl anion 1. These results contrast with the previous theoretical estimates, where the propynl-l-yl anion 1 is 2-3 kcal mol⁻¹ lower in energy than the allenyl anion 2. The activation energies of the intramolecular hydrogen transfer in the 1 → 2 conversion reactions are 63.5 kcal mol⁻¹ at the MRCI+Q level of theory with the aug-cc-pVTZ basis set including the zero-point energy corrections. The adiabatic electron affinity of the planer propargyl (H₂CCCH) radical, which is the global minimum of the C₃H₃ radical, is calculated to be 0.976 eV (after correction for the zero-point energy changes) at the CCSD(T) level of theory with the aug-cc-pVTZ basis set. The present electron affinity is in fairly good agreement with the experimental one (0.893 eV) observed by Oakes and Ellison.