Search results for "Ground state"
showing 10 items of 928 documents
An "S"-shaped pentanuclear CuII cluster derived from the metal-assisted hydrolysis of pyCOpyCOpy: structural, magnetic and spectroscopic studies.
2007
Reaction of [Cu2(O2CMe)4(H2O)2] with 2,6-di-(2-pyridylcarbonyl)-pyridine (pyCOpyCOpy or dpcp) in MeCN–H2O 10 : 1, led to the pentanuclear copper(II) complex [Cu5(O2CMe)6{pyC(O)(OH)pyC(O)(OH)py}2] (1) which crystallizes in the triclinic P space group. The copper(II) atoms are arranged in an “S”-shaped configuration, and are bridged by the doubly deprotonated bis(gem-diol) form of the ligand, pyC(O)(OH)pyC(O)(OH)py2−. Magnetic susceptibility data indicate the interplay of both ferro- and antiferromagnetic intramolecular interactions stabilizing an S = 3/2 ground state. Fitting of the data according to a next-nearest-neighbour model {Ĥ = −[J1(Ŝ1Ŝ2 + Ŝ1′Ŝ2′) + J2(Ŝ2Ŝ3 + Ŝ3′Ŝ2′) + J3(Ŝ1Ŝ3 + Ŝ3′Ŝ…
Multiple Decay Mechanisms and 2D-UV Spectroscopic Fingerprints of Singlet Excited Solvated Adenine-Uracil Monophosphate
2016
The decay channels of singlet excited adenine uracil monophosphate (ApU) in water are studied with CASPT2//CASSCF:MM potential energy calculations and simulation of the 2D-UV spectroscopic fingerprints with the aim of elucidating the role of the different electronic states of the stacked conformer in the excited state dynamics. The adenine 1La state can decay without a barrier to a conical intersection with the ground state. In contrast, the adenine 1Lb and uracil S(U) states have minima that are separated from the intersections by sizeable barriers. Depending on the backbone conformation, the CT state can undergo inter-base hydrogen transfer and decay to the ground state through a conical …
Molecular Sensors for Moisture Detection by Mössbauer Spectroscopy
2002
A parameter of importance in various industrial and commercial applications is sensitivity to moisture. A new class of molecular sensors which enable the qualitative and quantitative determination of air moisture (high selectivity and sensitivity) by application of Mossbauer spectroscopy as the probe technique has been investigated. The electronic properties of the iron-containing sensor depend upon the presence of moisture which is taken up by it and this process is accompanied by a change in electronic spin ground state which can be detected by Mossbauer spectroscopy. The sensor is suitable for in-field and industrial application using the recently developed Mossbauer spectrometer MIMOS I…
A Trinuclear Copper(II) Cryptate and Its μ3-CO3 Cascade Complex: Thermodynamics, Structural and Magnetic Properties
2011
The 2,4,6-triethylbenzene-capped hexaamine macrobicycle with pyridyl spacers (pyr) was able to coordinate three copper(II) ions within its cavity. Potentiometric studies performed at 298.2 K in MeOH/H(2)O (50:50 v/v) and at ionic strength 0.10 mol dm(-3) in KNO(3) revealed that trinuclear species predominate in solution from pH 5.0, the hydroxo complexes being the main species, which start forming at unusual very low pH values. The single-crystal X-ray determination of the trinuclear complex showed that the three copper centres have square-planar geometry, arranged in an almost equilateral triangle, and have carbonate bridging the three metal centres. The presence of carbonate resulted from…
Synthesis, molecular and electronic structures of a paramagnetic trimetallic cluster containing an unusual Mo3(μ3-Se)2(μ-Se)3 core
2014
Abstract The electron precise [Mo3(μ3-Se)(μ-Se)3(dppe)3Br3]+ incomplete cuboidal complex, with six cluster skeletal electrons (CSE), was converted into the paramagnetic bicapped [Mo3(μ3-Se)2(μ-Se)3(dppe)3]+ cluster (1+), with an unusual seven metal electron population, by treatment with elemental Ga. The cluster core consists of an almost equilateral Mo3 triangle (Mo–Mo distances are in the range 2.7583(7)–2.7748(7) A with an average value of 2.77(3) A), capped by two selenide ligands. The remaining selenium atoms bridge adjacent metal atoms, defining a virtually planar Mo3(μ-Se)3 unit, with the capping Se atoms positioned above and below this plane. The new complex possesses a doublet grou…
Multiplicity of ground states for the scalar curvature equation
2019
We study existence and multiplicity of radial ground states for the scalar curvature equation $$\begin{aligned} \Delta u+ K(|x|)\, u^{\frac{n+2}{n-2}}=0, \quad x\in {{\mathbb {R}}}^n, \quad n>2, \end{aligned}$$when the function $$K:{{\mathbb {R}}}^+\rightarrow {{\mathbb {R}}}^+$$ is bounded above and below by two positive constants, i.e. $$0 0$$, it is decreasing in (0, 1) and increasing in $$(1,+\infty )$$. Chen and Lin (Commun Partial Differ Equ 24:785–799, 1999) had shown the existence of a large number of bubble tower solutions if K is a sufficiently small perturbation of a positive constant. Our main purpose is to improve such a result by considering a non-perturbative situation: we ar…
Multiplicity of Radial Ground States for the Scalar Curvature Equation Without Reciprocal Symmetry
2022
AbstractWe study existence and multiplicity of positive ground states for the scalar curvature equation $$\begin{aligned} \varDelta u+ K(|x|)\, u^{\frac{n+2}{n-2}}=0, \quad x\in {{\mathbb {R}}}^n\,, \quad n>2, \end{aligned}$$ Δ u + K ( | x | ) u n + 2 n - 2 = 0 , x ∈ R n , n > 2 , when the function $$K:{{\mathbb {R}}}^+\rightarrow {{\mathbb {R}}}^+$$ K : R + → R + is bounded above and below by two positive constants, i.e. $$0<\underline{K} \le K(r) \le \overline{K}$$ 0 < K ̲ ≤ K ( r ) ≤ K ¯ for every $$r > 0$$ r > 0 , it is decreasing in $$(0,{{{\mathcal {R}}}})$$ ( 0 , R ) and increasing in $$({{{\mathcal {R}}}},+\infty )$$ ( R , + ∞ ) for a certain $${{{\mathcal {R}}}}&g…
Mössbauer effect study of the electronic ground state of iron(II)in tris(2-chlorophenanthroline)iron(II) perchlorate
1976
Abstract Mossbauer spectra of [Fe(2-Cl-phen) 3 ](ClO 4 ) 2 ·H 2 O have been measured in the temperature range 293 − 5 K. The spectra indicate that the iron atom in this compound possesses a spin quintet ground state throughout the temperature range under study, in contradiction to the suggested high spin-low spin transition, which has been concluded from a magnetic susceptibility study by other authors. From a theoretical analysis of the temperature dependence of the quadrupole splitting, with trigonal distortion, spin-orbit coupling, and effects of covalency taken into account, the ground term of iron(II) in this compound has been elucidated as being 5 A 1 ( 5 T 2g ), separated from the 5 …
Transition state theory thermal rate constants and RRKM-based branching ratios for the N((2)D) + CH(4) reaction based on multi-state and multi-refere…
2012
International audience; Multireference single and double configuration interaction (MRCI) calculations including Davidson (+Q) or Pople (+P) corrections have been conducted in this work for the reactants, products, and extrema of the doublet ground state potential energy surface involved in the N(2D) + CH4 reaction. Such highly correlated ab initio calculations are then compared with previous PMP4, CCSD(T), W1, and DFT/B3LYP studies. Large relative differences are observed in particular for the transition state in the entrance channel resolving the disagreement between previous ab initio calculations. We confirm the existence of a small but positive potential barrier (3.86 +/- 0.84 kJ mol-1…
Formation of linear Ni nanochains inside carbon nanotubes: Prediction from density functional theory
2013
Abstract First principles calculations have been performed to investigate the ground state properties of monoperiodic single-walled carbon nanotubes (CNTs) containing nanochain of aligned Ni atoms inside. Using the PBE exchange-correlation functional ( E xc ) within the framework of density functional theory (DFT) we predict the clusterization of Ni filaments in ( n ,0) CNTs for n ⩾ 9 and for ( n , n ) CNTs for n ⩾ 6. The variations in formation energies obtained for equilibrium defective nanostructures allow us to predict the most stable Ni@CNT compositions. Finally, the electronic charge redistribution has been calculated in order to explore intermolecular properties leading to stronger…