Estimation of bond energies from mulliken overlap populations

Haslingerová, I.

doi:10.1007/bf01588769

Cited by 10 publications

(8 citation statements)

References 7 publications

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“…The bonding topology in the HG series provides additional insights to the effect of composition as x increases from the view point of internal crystal cohesion. The calculated bond order (BO) values are a measure of strength and stiffness of the bond for each atomic pairs . Discussion on the BO in relation to crystal cohesion has been applied to the CSH crystals .…”

Section: Results and Implicationsmentioning

confidence: 99%

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Structure and properties of hydrogrossular mineral series

2017

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The hydrogrossular (HG) mineral series (Ca3Al2(SiO4)3−x(OH)4x; 0≤x≤3) are water‐bearing minerals found in the upper part of the Earth's mantle and as well as on its surface. They are vital to the planet's hydrosphere under different hydrothermal conditions. The composition and structure of this mineral series are important in geoscience and share many commonalities with cement and clay materials. Other than the end‐members of the series grossular (x=0) and katoite (x=3) which have a cubic garnet structure, the structures of the intermediate‐members are totally unknown. We used large‐scale ab initio modeling to investigate the structures and properties for HG series for x=0, 0.5, 1, 1.5, 2, 2.5, 3. Results indicate that for x>0 and x<3, the structures are tetragonal or nearly tetragonal, which partially justify that this garnet family is known to be cubic or pseudocubic. We also show that there are structural changes related to the disorder introduced with the composition mixing of SiO4 tetrahedra and AlO6 octahedra in the series. Based on the models constructed, the mechanical and interband optical properties of the HG series are calculated. For grossular and katoite, results are in good agreement with the available experimental data. The calculated electronic structure, total bond order explains the atomistic origin of the change in the compressibility of the series. Careful analysis of patterns of these results indicates that the series can be roughly divided into three regions: region I (x=0‐0.75), region II (x=0.75‐2.25), and region III (x=2.25‐3) with high, intermediate, and low Si/H ratio respectively. We also point out the inappropriateness of using the ill‐defined concept of treating O4H4 as a compressible structural unit in interpreting the structure and properties of HG series. Furthermore, the phonon spectra of grossular and katoite are calculated.

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Section: Results and Implicationsmentioning

confidence: 99%

“…The calculated bond order (BO) values are a measure of strength and stiffness of the bond for each atomic pairs. 60 Discussion on the BO in relation to crystal cohesion has been applied to the CSH crystals. 49 Figure 5A in the form of BO vs bond length (BL) plots.…”

Section: Interatomic Bondingmentioning

confidence: 99%

Structure and properties of hydrogrossular mineral series

2017

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“…As one cannot distinguish between bonding and antibonding character in the S matrix one uses the OP matrix: A positive sign means a bonding interaction, a negative sign antibonding. A vanishing OP denotes a non‐bonding interaction . Looking at the total S and the total OP (summed up over all occupied states) for the diamond core one can rule out any S–S interaction, as both values are one magnitude smaller than for the Cu Cu interaction, see Table .…”

Section: Resultsmentioning

confidence: 99%

Optical response of the Cu₂S₂ diamond core in (NGuaS)₂Cl₂

et al. 2016

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Density functional theory (DFT) and time-dependent DFT calculations are presented for the dicopper thiolate complex Cu2 (NGuaS)2 Cl2 [NGuaS=2-(1,1,3,3-tetramethylguanidino) benzenethiolate] with a special focus on the bonding mechanism of the Cu2 S2 Cl2 core and the spectroscopic response. This complex is relevant for the understanding of dicopper redox centers, for example, the CuA center. Its UV/Vis absorption is theoretically studied and found to be similar to other structural CuA models. The spectrum can be roughly divided in the known regions of metal d-d absorptions and metal to ligand charge transfer regions. Nevertheless the chloride ions play an important role as electron donors, with the thiolate groups as electron acceptors. The bonding mechanism is dissected by means of charge decomposition analysis which reveals the large covalency of the Cu2 S2 diamond core mediated between Cu dz2 and S-S π and π* orbitals forming Cu-S σ bonds. Measured resonant Raman spectra are shown for 360- and 720-nm excitation wavelength and interpreted using the calculated vibrational eigenmodes and frequencies. The calculations help to rationalize the varying resonant behavior at different optical excitations. Especially the phenylene rings are only resonant for 720 nm. © 2016 Wiley Periodicals, Inc.

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“…The bond order (BO) between each pair of atoms represents the quantitative measure of the bond stiffness and strength 22 . They are important in revealing the origin of internal cohesion in the CSH crystals.…”

Section: Introductionmentioning

confidence: 99%

Quantum Mechanical Metric for Internal Cohesion in Cement Crystals

Dharmawardhana

Misra

Ching

2014

Sci Rep

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Calcium silicate hydrate (CSH) is the main binding phase of Portland cement, the single most important structural material in use worldwide. Due to the complex structure and chemistry of CSH at various length scales, the focus has progressively turned towards its atomic level comprehension. We study electronic structure and bonding of a large subset of the known CSH minerals. Our results reveal a wide range of contributions from each type of bonding, especially hydrogen bonding, which should enable critical analysis of spectroscopic measurements and construction of realistic C-S-H models. We find the total bond order density (TBOD) as the ideal overall metric for assessing crystal cohesion of these complex materials and should replace conventional measures such as Ca:Si ratio. A rarely known orthorhombic phase Suolunite is found to have higher cohesion (TBOD) in comparison to Jennite and Tobermorite, which are considered the backbone of hydrated Portland cement.

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Estimation of bond energies from mulliken overlap populations

Cited by 10 publications

References 7 publications

Structure and properties of hydrogrossular mineral series

Structure and properties of hydrogrossular mineral series

Optical response of the Cu₂S₂ diamond core in (NGuaS)₂Cl₂

Quantum Mechanical Metric for Internal Cohesion in Cement Crystals

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Estimation of bond energies from mulliken overlap populations

Cited by 10 publications

References 7 publications

Structure and properties of hydrogrossular mineral series

Structure and properties of hydrogrossular mineral series

Optical response of the Cu2S2 diamond core in (NGuaS)2Cl2

Quantum Mechanical Metric for Internal Cohesion in Cement Crystals

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Product

Resources

About

Optical response of the Cu₂S₂ diamond core in (NGuaS)₂Cl₂