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The effect of methanol group on absorption of SO2 by diamine compound was investigated via density functional theory. It was observed that the presence of methanol group increases the binding energy of absorption. According to the result of binding energy, the di-methanol-diamine (D-b) structure can be the best diamine for SO2 absorption and the results of Gibbs energy verified the most thermodynamically favorable structure. According to the weak energy analysis, the absorption interactions in D-b are both vdW and HB interactions. The result of second-order perturbation energy showed that the interaction of the donor atom of diamine with antibonding orbital of S-O (BD*S) in D-b is the highest which points to the most stable structure. According to molecular frontier orbital analysis, it can be concluded that the absorption of SO2 on the diamines is not very strong and desorption of SO2 would be easier than that the strong chemical absorption.

A detailed orbital analysis of two seemingly ordinary classes of complexes of group 12 dications, [M(NH3)4]2+ and [M(PH3)4]2+, M = Zn, Cd, Hg, holds a surprise. The PH3 complexes are text-book examples of tetrahedral bonding, but in the ammine complexes calculations reveal a remarkable degree of mixing between occupied M (n-1)d and NH3 σπ orbitals. A perturbation-based Fock matrix examination traces the origin of this mixing to an energy resonance and improved overlap of interacting orbitals for NH3 ligands. The possibility of probing this anomalous mixing with valence-to-core X-ray emission spectroscopy (V2C XES) is discussed.

Ever since the proposal of the exotic concept “planar tetra-coordinate carbon” (ptC), continuous endeavors have been hotly devoted to the design and characterization of molecules with planar tetra- or hyper-coordinate atomic centers. In sharp contrast to the big ptC family, examples with the planar penta-coordinate carbon (ppC) have remained very scarce, only including CAl 5 + , CAl 4 Be, CAl 3 Be 2 , CAl 2 Be 3 2 and CBe 5 E (E = Al, Ga). To enrich the member of ppC, in this work, we report our global isomeric characterization of CAl 4 X + (X = Al, Ga, In and Tl) at the CCSD(T)/def2-TZVPP//B3LYP/def2-TZVP level with zero-point energy correction, among which, to our knowledge, systems with X = Ga, In and Tl have not been considered previously. For CAl 5 + , besides confirming previous computational study that ppC is the ground structure, we find a new isomer (4th) among the former seven species here. Promisingly, by means of the structural and orbital analysis, CAl 4 Ga + is a novel ppC structure though the penta-coordinate ligands of C are not average due to the Al → Ga substitution. For the heavier CAl 4 X + (X = In and Tl), there does not exist a ppC structure and the global isomer can formally be considered as an X + adsorbed to the neutral T d -like CAl 4 . In the order of X = Al, Ga, In and Tl, the preference of ppC over the T d -C decreases for CAl 4 X + , which could be interpreted by the decreased covalent ability. The newly disclosed CAl 4 Ga + awaits future mass spectrometry characterization.

Many reports and patents address tracking-type systems to complete and optimized the acquisition of solar energy. However, fixed-type systems contribute the most of the market to the solar photovoltaic system (SPVS) for the existing buildings. Based on this fact, it is important to discuss and understand the feasible setup parameters to achieve the optimum radiation-collection-efficiency of a fixed-type system. The purpose of the present report is to provide the methodology and to investigate the optimum angles of the system facilities through minimum mathematics. The calculations show that for the demonstrated locations, the maximum efficiency for the whole year of a fixed-type system can reach more than 61% efficiency, compared to a total tracking system at the same location and time intervals. Based on these calculations, the appropriate optical system can be designed to improve system performance for the majority buildings requirements in any location.

A combination of computational techniques was used to study the phosphorescent emission of complexes with general formula [Cu 3 ( μ -dppm) 3 ( μ 3 - η 1 -C≡CAr) 2 ]BF 4 , with Ar = aryl. The calculated S 0 –T 1 transition energies are in good agreement with the experimental emission maxima. Natural Transition Orbital analysis of the lowest triplet states indicates that the emission largely originates from a π → π* excitation on one of the two acetylide ligands with only a marginal participation of the trinuclear copper(I) cluster, unlike previously proposed.

By using broken-symmetry hybrid-DFT (UB3LYP and UB2LYP) calculation, the effective exchange integrals (J values) of [Cr(C5(CH3)5)2]+[TCNE]−[Cr(C5(CH3)5)2]+ and [Mn(C5(CH3)5)2]+[TCNQ]−[Mn(C5(CH3)5)2]+ were determined theoretically. Those calculated models were reduced to 3-spin-sites models from X-ray crystallographic data of charge transfer 3D crystal. The calculated results showed that effective exchange integrals were positive and the signs of spin densities on the cyclopentadienyl rings were negative. These results supported the so-called McConnell I mechanism for ferromagnetism proposed by Kollmar et al. and our previous calculations. Natural orbital analysis made it clear that the orbital overlap between SOMO on metals and SOMO on TCNE or TCNQ cations was nearly zero. These results indicated that orbital orthogonality was an important key factor for explaining the ferromagnetism of those systems.

Interest in the deployment of tethered satellites has led to a need for preliminary orbit determination methods which are capable of distinguishing tethered satellites from untethered ones. Classical preliminary orbit determination methods, which are used for Keplerian satellites, generally require two or more position vectors along with their respective observation times in order to determine a preliminary orbital element set. These conventional methods, however, are unable to distinguish between Keplerian and tethered satellites, whose motion is modified due to the presence of a tether force. The use of conventional methods result in the calculation of inaccurate orbital elements if the observed satellite is part of a tethered satellite system. Modifications have been made to four classical preliminary orbit determination methods in order to allow for the identification of tethered satellites. These modifications provide the ability to distinguish between a tethered satellite and an untethered one. This paper applies these modified preliminary orbit determination methods to the problem of the identification of a tethered satellite. The performance of these methods is evaluated through scenarios of differing tether lengths and levels of observation error, and results are compared in order to determine the most accurate method.

The doubly Si-bridged ansa -tungstenocene, [W(η 5 -C 5 H 3 ) 2 (SiMe 2 ) 2 ], ( a -Si 2 Cp 2 W) is calculated to have singlet and triplet states of comparable energy, in contrast to other tungstenocenes which have triplet ground states. Therefore, on an SCF energy surface there is no barrier to formation of a sigma complex with methane, and formation of a methyl hydride is exo-energetic by −125 kJ mol −1 . Orbital analysis of the tungstenocenes shows that the singlet ground state is favoured by a ring conformation that stabilizes the 2b 1 orbital by back donation, and that a double ansa bridge promotes this ring conformation.

Density functional theory has been used to explore the energetics and bonding of the symmetric and unsymmetric isomeric sandwich complexes (η 5 -C 5 H 5 ) 2 M, (η 4 -C 4 H 4 )M(η 6 -C 6 H 6 ), and (η 3 -C 3 H 3 )M(η 7 -C 7 H 7 ) (M = Fe, Ru, Os). For each metal atom, the symmetric “5–5” metallocene was found to be the most stable isomer, with the “4–6” and “3–7” isomers ca. 40 and 80 kcal/mol higher in energy, respectively. Bonding analysis shows that (η 4 -C 4 H 4 )Fe(η 6 -C 6 H 6 ) is best considered as a (η 4 -C 4 H 4 )Fe fragment interacting with a C 6 H 6 ligand, although the interactions become less separable as the metal is changed to Ru and Os. Similarly, the dominant bonding in (η 3 -C 3 H 3 )M(η 7 -C 7 H 7 ) is that of a M(η 7 -C 7 H 7 ) perturbed by the interaction with a C 3 H 3 ligand.

A complete orbital analysis of two isoelectronic complexes of trifluorobenzene (TFB), TFB ⋯ F − and TFB ⋯ Na + , as models for anion-π and cation-π interactions, respectively, has been performed at the MP2/6-31++G** level of theory. There are important orbital differences between both interactions, which are discussed in detail herein.

The ground-state conformations of 2-dialkylaminomethylphenol and 2-dialkylaminomethyl-4-methylphenol bearing two different coordination sites were analyzed by means of the semi-empirical AM1 method. Complexation of these ligands was investigated theoretically as boron and zinc complexes. Prevision of the possible bonding between the aminophenol ligands and the BF 2 + fragment was made using the frontier orbital concept. This concept was successfully extended to the prediction of the bonding with ZnCl 2 , showing theoretically that, in these cases, boron complexes can be safely used for modeling zinc complexes. The calculated ligand reactivity and the complex stability were in agreement with experimental results.

The application of missing-orbital analysis to molecular hyperpolarizability β obtained by a simplified sum-over-states calculation, allows one to study the effects of the π conjugation extension on both diagonal β zzz and off-diagonal β zxx components for C 2v molecules (the z -axis being the principal one). Extension of the z -length in aminonitropolyacetylenes by increasing the number of acetylene units increases β zzz but β zxx remains unchanged. Conversely, β zxx increases significantly with only a slight increase in β zzz if the π conjugation is extended mainly in the x -direction for 1,3-diamino-4,6-dinitrobenzene by replacing benzene with a fused-ring or inserting acetylene units between the substituents and benzene. These are ascribable to changes in the charge-transfer structure by the π extension.

The first-order hyperpolarizability components, βzzz and βzxx, for C2v molecules (the z axis being the principal axis) are analyzed after simplified sum-over-states calculations. Compared with p-nitroaniline (PNA), βzxx is three times enhanced by x-extended π conjugation realized by a bulky substrate in 9-amino-10-nitroanthracene (ANA) and by multiple substitutions in 1,5-diamino-2,4-dinitrobenzene (DDB). While ANA shows βzzz unchanged because its z-directed charge transfer (CT) is similar to PNA, DDB has a β zzz 1 3 of PNA, which is reduced by two weak CTs introduced by two ortho-positioned donor-acceptor pairs on both sides of the z axis.

The off-diagonal component of the first-order hyperpolarizability tensor βzxx of C2v molecules, e.g. substituted polyynes and benzenes, has been calculated by a simplified sum-over-states method. The missing-orbital analysis of the calcualted results reveals that excitations from a2 and b2 orbitals contribute cooperatively to βzxx, suggesting an insufficiency of the two-state model to describe βzxx. Increasing the number of occupied a2 orbitals enhances the magnitude of βzxx. For the C2v molecule with a2 orbitals widely extended in the x direction, βzxx can exceed βzzz, as found in 9-amino-10-cyanoanthracene having a βzxx about twice as large as βzzz.

The simplified sum-over-states (SOS) and missing-orbital analysis methods are introduced. The former aims to calculate the molecular polarizabilities in the framework of ab initio SCF theory, and the latter to analyze the calculated polarizabilities. The utility of the combination of these methods is demonstrated for the benzene derivatives, e.g. p -nitroaniline (PNA) and p -cyanoaniline (PCA). The calculated first-order hyperpolarizabilities (β) agree well with those of both CPHF calculations and experimental results. The missing-orbital analysis shows that β for PCA is contributed by both forward and backward charge transfer (CT) related to “out-of-plane” and “in-plane” orbitals, respectively. In contrast, β for PNA is confirmed to be explained fully by the conventional two-state model characterized by strong forward CT.

Analysis of Seasat laser range data over long arcs has identified geomagnetic modelling within atmospheric density models as a significant source of error. In particular, a major deficiency is the absence or mis-modelling of persistence of a geomagnetic event at heights near 800km. A logical step is to refine persistence and the geomagnetic model parameters within the least-squares differential correction procedure of the orbital refinement. To investigate the feasibility of this approach, persistence has been studied and parameters adjusted within the J71 atmospheric model and its variant due to Slowey, JS84. In J71 two parameters were derived by combination of 7 or 8 Seasat arcs. No advantage was found by refining the 3 extra parameters within JS84. The validity of the solution has been tested on 17 Starlette arcs for which the level of improvement is significant, particularly during levels of high geomagnetic activity. This is the first occasion that atmospheric density parameters have been derived within the orbital analysis data-reduction procedure and paves the way for more extensive analyses in the future.

One-electron properties calculated from SCF Xα SW/MT and near-HF functions for water are compared. A regional orbital analysis is used to assess the differences between the functions.

The results obtained in a quantitative orbital analysis of the ab initio SCFMO computations performed on hydroxylamine and thiohydroxylamine are described. The analysis is based on the use of fragment localized MOs and the energy effects associated with their interactions are estimated, in the framework of the ab initio SCF—MO computations, using PMO expressions. In particular the factors are analyzed which control the conformational preference in these molecules, and the effect of the sulphur 3d orbitals upon conformational stability is discussed.

A least-squares multiple linear regression is performed on orbital decay density data obtained from precise orbital analysis of 22 low-perigee (130–160 km) Air Force satellites. Variations related to solar activity, the semi-annual effect, geomagnetic activity, and the zenith angle of the Sun are in agreement with the model of Jacchia (1971). Density variations in longitude and latitude are also deduced and compared with recent results from other investigations within this altitude regime.

Interaction between both a copper atom and the Cu(I) positive ion with a water molecule has been studied by means of two different CI approaches: CIPSI (selected CI) and CAS-CI. Corresponding orbital analysis has been used to interpret the bonding at the SCF level. The multireferential CI wavefunction has also been interpreted for Cu/H2O and Cu(I)/H2O systems. The results show that the interaction for the Cu(I)/H2O system is electrostatic (mainly due to polarization forces), whereas the dispersion forces are the main factor responsible for the bonding in the Cu/ H2O system.