On the energy difference between the lP and 3P states of the beryllium isoelectronic sequence

Wave functions of the ¹S (ground state), ³P and ¹P states for the beryllium isoelectronic sequence have been obtained in various approximations. The HF ²p orbitals for the ¹P and ³P states are similar except for Be, where the ²p orbital is quite diffuse for the ¹P state. The difference between the experimental E(¹P) – E(³P) and the HF E(¹P) – E(³P) is 0.62 eV for Be and 1.17 ～ 1.40 eV for B⁺ ～ F⁵⁺. The disagreements are attributed to the correlation effects between the 2s and 2p electrons. This is confirmed by ci calculations. It is shown that a limited basis SCF calculation reproduces the above feature of the HF results if we treat the orbital exponents as the variational parameters. The use of the Slater values for the orbital exponents is shown to be inadequate especially for the Be ¹P state. The conclusions of this paper will be useful for discussing the V–T separations of H₂ and C₂H₄.     

Cubic phases of binary systems of 4′-n-tetradecyloxy-3′-nitrobiphenyl-4-carboxylic acid (ANBC-14)-n-alkane

The phase behaviour of the binary systems 4′- ⁿ -tetradecyloxy-3′-nitrobiphenyl-4-carboxylic acid (ANBC-14)- ⁿ -alkane ( ⁿ -tetradecane or ⁿ -hexadecane) was investigated by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction. The phase behaviour was a function of temperature ( ^T ) and the effective carbon number of the system ( ^n*), where ^n* involves carbon atoms both from the alkoxy group of ANBC-14 and from the ⁿ -alkane added. ANBC-14 shows no cubic phase, but the addition of ⁿ -alkane induced cubic phases when ^n*≧c. 15. An interesting point is that the type of cubic phase is ^Ia 3 ^d for 15^≦n*≦17, while an ^Im 3 ^m type is formed for 18^≦n*≦20. Furthermore, for ^n* = 22, two types of cubic phase, one with ^Im 3 ^m symmetry in the low temperature region and the other with ^Ia 3 ^d in the high temperature region, were observed both on heating and cooling. The phase diagram with respect to ^T and ^n* is very similar to that of pure one-component ANBC- ⁿ , which is a function of ^T and the number of carbon atoms in the alkoxy group ⁿ .     

Basis set quality versus size II. Approximate GTO wave functions for second row transition metal atoms

Basis sets ranging in size from (16, 10, 7) to (20, 14, 11) have been derived for the atoms Y–Cd. Separate sets represent the energy optimized wave functions for each of the s²dⁿ, s¹dⁿ⁺¹, and s⁰dⁿ⁺² configurations. The energies from the largest sets are within 3 mhartrees of the values obtained in numerical Hartree–Fock calculations. Reasonable Hartree–Fock s²dⁿ– s¹dⁿ⁺¹ and s²dⁿ– s⁰dⁿ⁺² excitation energies may be obtained either using the largest basis sets, or using d-orbitals optimized for the s⁰dⁿ⁺² configurations. The basis sets are slightly unbalanced in favor of the s-functions and in disfavor of the d-functions, but various alternative basis sets may be derived by combining parts of the five parent sets. The convergence of radial expectation values is discussed.     

Theoretical study of low‐lying electronic states of the LiRb+ molecular ion: Structure,spectroscopy and transition dipole moments

The electronic structure and the spectroscopic properties for low‐lying electronic states of the LiRb⁺ molecular ion, dissociating into Li (2s, 2p, 3s, 3p, 3d, 4s, and 4p) + Rb⁺ and Li⁺ + Rb (5s, 5p, 4d, 6s, 6p, 5d, and 7s), have been investigated using an ab initio approach based on non‐empirical pseudo potentials for the Li and Rb cores and parametrized l‐dependent polarization potential. We have determined the adiabatic potential energy curves and their spectroscopic constants for many electronic states of ²Σ⁺, ²Π, and ²Δ symmetries. A satisfying agreement, for the spectroscopic constants, has been obtained for the ground and the first excited states with the available theoretical works. Potential energy curves were presented, for the first time, for the higher excited states. In addition, we have localised and analysed the avoided crossings between electronic states of ²Σ⁺ and ²Π symmetries. Their existences can be related to the interaction between the potential energy curves and to the charge transfer process between the two ionic systems Li⁺Rb and LiRb⁺. Moreover, we have determined the transition dipole moments from X²Σ⁺ and 2²Σ⁺ states to higher excited states of ²Σ⁺ and ²Π symmetries. For our best knowledge, no experimental data on the LiRb⁺ molecular ion is available. These theoretical data can help experimentalists to optimize photoassociative formation of ultracold LiRb⁺ molecular ion and their longevity in a trap or in an optical lattice. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012     

Carbon-13 nuclear magnetic resonance spectra of exo- and endo-2-norbornyltrimethyl-stannanes: Corrected assignments

The ¹³C NMR spectra of pure exo-2-norbornyltrimethylstannane and a mixture of the exo- and endo-isomers have been recorded. ¹H–¹³C polarization transfer spectra have been obtained and require the previously reported assignments for C-3 and C-4 in the exo-isomer to be reversed. The reported assignments for the endo-isomer are correct. The new assignment for C-4-exo [with J(¹¹⁹Sn,¹³C) vic=12 Hz, instead of the previously assigned J(vic)=23 Hz], has a very minor effect on the nature of the Karplus curve [for ³J(¹¹⁹Sn,¹³C)] generated previously.     

Ab initio study on NH+: Transition dipole moments,transition probabilities,and radiative lifetimes

The transition electric dipole moments between low-lying valence states of NH⁺ are calculated by an ab initio effective valence-shell Hamiltonian (H^v) method. The H^v calculated transition moments are found to be in good agreement with those by other accurate ab initio methods. The spontaneous emission probabilities for the A²− → X²Π, B²Δ → X²Π, and C²−⁺ → X²Π transitions of NH⁺ are computed. Also, radiative lifetimes for A²∑⁻, B²Δ, and C²∑⁺ states are all theoretically determined using the potential energy functions by H^v. Also, the H^v results are well compared with those computed using the Morse potentials and the rkr potentials which are obtained from experimental data. © 1996 John Wiley & Sons, Inc.     

The collisional quenching of electronically excited arsenic atoms As(42DJ) and As(42PJ), studied by time-resolved attenuation of atomic resonance radiation

A kinetic investigation of electronically excited arsenic atoms in the low-lying states, As(4p^{3 2}D_J) and As(4p^{3 2}P_J), ca. 1.33 and 2.28 eV, respectively, above the 4⁴S_3/2 ground state, has been carried out by atomic absorption spectroscopy. Atoms in these optically metastable states were generated by the pulsed irradiation of suitable arsenic compounds (AsMe₃ for ²D and AsCl₃ for ²P) in different spectral regions and monitored photoelectrically by time-resolved attenuation of atomic resonance radiation. Rate constants for the deactivation of these two states are reported for a range of collision partners. The data are compared with those of the analogous states of lighter atoms in group V, namely, P(3²D_J, 3²P_J) and N(2²D_J, 2²P_J), and discussed in terms of spin and orbital symmetry considerations.     

Forbidden electric quadrupole transitions between even OIII levels

The relativistic CI method is used to determine transition probabilities for electric quadrupole transitions between the 1s ² 2s ² 2p ² (³ P ₀,³ P ₂,¹ D ₂) and 1s ² 2p ^{4 3} P ₂ even levels of OIII. The variation of the results with the number of configurations used is discussed, both for the Coulomb and the Babushkin (length) gauge.     

A relativistic CI study on OIII: wavefunctions,excitation energies and transition probabilities

The relativistic CI method is used to determine N-electron wavefunctions for the 1s ² 2s ² 2p ² (³ P ₀,³ P ₂,¹ D ₂), 1s ² 2p ^{4 3} P ₂ even levels, and the 1s ²2s2p ³ (³ D ₁,³ P ₁,³ S ₁,¹ P ₁), 1s ²2s ²2p3s (³ P ₁ and¹ P ₁), 1s ²2s ²2p3d (³ D ₁,³ P ₁,¹ P ₁)J=1 OIII levels. Excitation energies and emission probabilities between these levels are reported in the electric dipole approximation, both for the Coulomb and the Babushkin gauges.ns, p,np,nd- andnd (n17) numerical basis functions have been used for the construction of CSF's entering the CI expansion for the ASF's of these levels. Radiative matrix elements of the type calculated here within the framework of the relativistic CI method, may be used in laser assisted spectroscopic studies of atoms and ions.     

Muscle and scale isotopic offset of three fish species in the Mediterranean Sea: Dentex dentex,Argyrosomus regius and Xyrichtys novacula

Diet information of organisms was traditionally acquired by the use of lethal techniques (gut content or muscle δ¹³C and δ¹⁵N isotopic ratios). An increase in the number of isotopic ratio studies and the vulnerability of some species have led to increased use of non‐lethal methodologies for conservation purposes. In the present work we have compared the δ¹³C and δ¹⁵N isotopic signals of muscle and scales of three different fish species in order to test fish‐scale sampling as a non‐lethal technique in fish trophodynamics. A positive correlation was found between muscle and scales in Argyrosomus regius and Xyrichtys novacula, while Dentex dentex showed no correlation due to the small length range of this species. The isotopic offset (Δ¹³C and Δ¹⁵N) between muscle and scales was significantly different among species (analysis of variance (ANOVA), p < 0.001) with Tukey's post‐hoc HSD indicating a tissue offset difference (p < 0.001) for both stable isotopes in all species, except for Δ¹³C between A. regius and X. novacula and for Δ¹⁵N between D. dentex and X. novacula (p > 0.05). Mean δ¹³C and δ¹⁵N values between species showed significant differences (paired t‐test, p < 0.01) between muscle and scale with an enrichment for δ¹³C and a depletion for δ¹⁵N. Spatial differences were found in the Δ¹³C of X. novacula between the studied locations, while no differences were found for Δ¹⁵N, indicating that non‐geographical differences should be considered in the application of scales instead of muscle for ¹⁵N, while for ¹³C differences in the geographical isotopic offset should be considered. Copyright © 2009 John Wiley & Sons, Ltd.     

Molecular dynamics simulation of brushes formed by star polyelectrolytes under theta solvent conditions

Using molecular dynamics simulations, we have studied polyelectrolyte brushes formed by partially or fully charged star polymers tethered on a planar surface under theta solvent conditions. The diagram of states for salt‐free solutions differs in the location of osmotic regime (OB) compared with the respective diagram reported by Borisov and Zhulina. In contrast, simulation results dictate that the OB regime appears for values of the ratio F /α ^?1/2 l_B ^?1 much larger than unity, which is the threshold of counterion localization, with F denoting the branch functionality, α the charged units fraction and l_B the Bjerrum length. The simulation results support that the brush height scaling laws H ～ α ² l_B F ^1.049S ³s ^?1 and H ～ α^0.302 F ^0.23S for the charged Pincus Brush (PB) and osmotic (OB) regimes, respectively, where S is the spacer length and s is the grafted area per star chain. The respective theoretical scaling laws are H ～ α ² l_B F ^1.88S ³s ^?1 and H ～ α ^1/2 F ^0.44S . © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55 , 1110–1117     

A Closed-Form Relation for Dimension-Dependent Two-Electron Matrix Elements of the Interelectronic Distance

The evaluation of matrix elements of two electron atoms is fundamental for the study of the electronic properties of those systems. We add to this knowledge by presenting an explicit expression for the matrix elements of the inverse of the interelectronic distance of two-electron atoms in any spatial dimension D. The basis functions used are the D-dependent hydrogenic wavefunctions {1s ²,2p ²,3d ²,4f ²,5g ²,...,21y ²,...}, extending and including, in this way, the results of the previous basis set {1s ²,2p ²,3d ²,4f ²}. The methodology used does not employ Fourier integral transforms as in previous works but hypergeometric transformation formulas.     

Elastic modulus of the crystalline phase of poly(cis 1,4-isoprene)

The crystalline elastic modulus of poly(cis 1,4-isoprene) has been measured by x rays and calculated by molecular mechanics. The experimental modulus is E = (2.3 ± 0.3) × 10⁹N m^?2. The calculated modulus is E = (8.8 ± 0.1) × 10⁹N m^?2 for chains in S⁺ cis S^?T conformation and E = (6.1 ± 0.1) × 10⁹N m^?2 for chains in S⁺ cis S+T conformation. The modulus calculated for a statistical structure including both conformation is E = (6.7 ± 0.1) × 10⁹N m^?2. The experimental modulus is thought to be a lower limit because of partial crystallinity of the sample. The chief mechanism of deformation is rotation around single bonds adjacent to the double bond.     

Study of Activation and Inhibition of Certain Metal Ions to Amylase Catalyzed Reaction by Microcalorimetry

IntroductionMostcomplicatedreactionshappenedinlivingcrea tures ,amongthemenzymecatalyzedreactionisanimpor tantclass .Itissignificantinboththeoryandpracticetoinvestigateenzymecatalyzedreaction .Therearemanyex perimentalmethodssuchasspectrophotometry ,titrimetry ,isotopemethod ,microcalorimetryandsoon ,inwhichmi crocalorimetryisanewoneduetoitshighsensitivityandaccuracy .Wecanstudythewholeprocessoftheheatef fectusingamicrocalorimeter .Sincetheabsorptionorpro ductionofheatisanintrinsicpropertyofe…     

New expansion of the Boys function

We propose a new expansion for the Boys function ∫₀¹t^2jexp(−r²t²) dt appearing in the calculation of molecular two-electron matrix elements if Gaussian basis sets are employed. This expansion involves a power series involving the terms C_{i, j}(τ) (r²−R²)ⁱ multiplied by exp(−τr²), where τ is an optimized parameter τ∈[0, 1]. The performances of the introduced expansion are discussed and illustrated by some numerical experiments. It appears that the proposed expansion is considerably shorter than the customary Taylor series, which in turn is the special case for τ=0. This is of some importance, particularly for higher j values. Further, the proposed expansion enables a single expression for calculating erf(x) for the whole range of variable x. The recursive relations for the expansion coefficients are derived and the truncation errors are estimated. A new method for calculating the Boys function by means of asymptotic series is represented too. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 68: 305–315, 1998     

Ab initio study of low-lying electronic states of the FNO2 molecule

Ab initio electronic structure calculations are reported for low-lying electronic states, ¹A₁, ¹A₂, ³A₂, ¹B₁, ³B₁, ¹B₂, and ³B₂ of the FNO₂ molecule. Geometric parameters for the ground state ¹A₁ are predicted by MRSDCI calculations with a double-zeta plus polarization basis set. The vertical excitation energies for these electronic states are determined using MRSDCI/DZ+P calculations at the ground-state equilibrium conformation. The oscillator strengths and radiative lifetimes for some electronic states are calculated based on the MRSDCI wave functions. © 1993 John Wiley & Sons, Inc.     

Thermodynamics of mixtures of hexane and heptane isomers with normal and branched hexadecane

Molar excess mixing enthalpies h ^E , Gibbs free energies g ^E and hence entropies s ^E have been obtained using calorimetry and the vapor sorption method at 25°C for hexane isomers+2,2,4,4,6,8,8-heptamethylnonane, a highly branched C ₁₆ . The h ^E and g ^E are negative while Ts ^E are positive, but small. The values are explained by the Prigogine-Flory theory through negative free volume contributions to h ^E and Ts ^E , counterbalanced in the case of Ts ^E by the positive combinatiorial Ts ^E for mixing molecules of different size. No contribution is seen from the interaction between methyl and methylene groups. The excess quantities are also obtained for hexane and heptane isomers mixed with n-hexadecane. Values of h ^E and Ts ^E are now strongly positive, while those of g ^E are only slightly less negative. The interpretation requires two recently advanced contributions in addition to those of the Prigogine-Flory theory: 1) a decrease of order when correlations of orientations between n-C ₁₆ molecules in the pure liquid are replaced in the solution by weaker correlations whose strengths depend on the shapes of the lower alkane isomers. For lower alkane isomers of the same shape, but highly sterically hindered, h ^E and Ts ^E are small, manifesting, 2) a negative contribution, ascribed to a rotational ordering of n-C ₁₆ segments on the sterically-hindered molecule. Enthalpy-entropy compensation is observed for these new contributions, arising from their rapid fall-off with increase of temperature.     

二元无机物标准熵 So298的拓扑研究

为了预测二元无机物的标准熵,基于分子图的连接矩阵和离子参数gi、qi,提出了一种新的连接性指数mQ, mG及其逆指数mQ’, mG’。 qi、gi定义为：qi=(1.1+Zi1.1) /(1.7+ni), gi=(1.4+Zi) /(0.9+ri+ri-1),其中Zi 、ni和 ri分别代表离子i的电荷数、最外层主量子数和半径。从0Q, 0Q’, 1G,和1G’,利用多元线性回归分析方法和人工神经网络方法,可以构建优良的QSPR模型。对371个二元无机物,其多元线性模型及神经网络模型的相关系数、标准偏差和平均绝对偏差分别是：0.9905, 8.29 J.K-1.mol-1, 6.48 J. K-1.mol-1, 0.9960, 5.37 J.K-1.mol-1 和 3.90 J.K-1.mol-1。留一法交叉验证表明,其多元线性模型具有良好的稳定性。两个模型对187个未进入模型的二元无机物的标准熵的预测值和实验值之间的相关系数、标准偏差和平均绝对偏差分别是：0.9897, 8.64 J. K-1.mol-1, 6.84 J. K-1.mol-1, 0.9957, 5.63 J.K-1.mol-1, 和 4.18 J.K-1.mol-1。研究表明,本文方法在预测二元无机物标准熵时比文献方法更有效,两种模型均能较精确的预测二元无机物的标准熵,且神经网络模型的预测结果更精确。     

Baseline assessment of doses and risk due to natural radionuclides in edible biota of Domiasiat,Meghalaya, India

Radiation dose-risk assessment was carried out for cereal species Brassica compestris var. dichotoma, Oryza sativa var. Shalum1, Zea mays, Lactuca indica, Cumunis sativum, and Clocasia esculanta due to naturally available radionuclides ⁴⁰K, ²³⁸U and ²³²Th in Domiasiat area. The activity in biota and corresponding soil was measured by precipitation method using NaI(TI) detector. Transfer factor (TF) was for Oryza spp. (1.00E−01-⁴⁰K, 8.76E−05-²³²Th, and 9.11E−05-²³⁸U), for Brassica spp. (5.39E−01-⁴⁰K, 8.17E−04-²³²Th and 2.96E−04-²³⁸U) and for Zea spp. (3.41E−01-⁴⁰K, 5.84E−05-²³²Th, 8.87E−05-²³⁸U) etc., respectively. A detailed physio-morphological study of the biota and extensive investigation of ecosystem was carried out for assessment. The data was modeled using FASSET for dose estimation and obtained total dose was 1.58E−04  \upmu Gy h^-1 \upmu \hbox{Gy}\,h^{-1} in Oryza spp., 2.87E−04  \upmu Gy h^-1 \upmu \hbox{Gy}\,h^{-1} Brassica spp. and 6.90E−03  \upmu Gy h^-1 \upmu \hbox{Gy}\,h^{-1} in Zea spp. etc. The dose was compared with the UNSCEAR dataset for screening level dose for biota. Zea spp. was more susceptible for the chronic radiation exposure.     

Accurate analytical self-consistent field wave functions for Tm2+ and Tm3+

The analytical expansion self-consistent field method was employed to perform ab initio calculations for the ground states of the rare-earth ions, Tm²⁺, 4f¹³, ²F, and Tm³⁺, 4f¹², ³H, (Z = 69). In each case the total number of basis functions used in the analytical expansions was 29, distributed as follows: 10, 8, 5, and 6, for the symmetries s, p, d, and f, respectively. All of the orbital exponents of the basis functions were optimized repeatedly, to the extent of the single-precision computer representation. Values of 〈rⁿ〉 for the 4f orbital of both ions are also presented, for the convenience of experimentalists.