246
12 Perspectives
(6) Defect formation improves the photocatalytic ability of TiO 2 by band
gap and workfunction reduction and carrier life extension through the
undercoordination-induced quantum entrapment and polarization—pining
dipoles. Transition from entrapment to polarization dominance occurs at a
critical size or surface curvasture.
(7) Water is the simplest among the molecular crystals as it contains equal number of
dangling protons and lone pairs. Lone pair and dangling proton are the primary
functional and structural units of molecular crystals. Molecular undercoordoination and electrostatic polarization shorten the H–O bond and lengthen the O:H
nonbond associated with strong polarization, which leads to a supersolid phase
that is elastoviscus, hydrophobic, less dense, mechanically and thermally more
stable. The supersolidity disperses the quansisolid phase boundaries to raise the
melting temperature and lowers the freezing point and evaporation of water ice.
(8) Spin-resolved polarization by atomic undercoordination and sp-orbital
hybridization could reconcile the skin and monolayer high-T C superconductivity and topological insulator edge superconductivity. The strength of spin-spin
coupling determines the T C and the conduction bandgap width; the localized
polarization determines the edge or skin paths of carrier travelling.
Findings not only demonstrate the power of the BOLS-NEP-ZPS and the APECS
strategies in complementing STM/S and PES but also the essentiality of the perspective of bonding and electronic dynamics associated with irregular atomic and
molecular coordination and orbital hybridization. Controlling the process of bond
and nonbond formation, dissociation, vibration, and relaxation and the associated
dynamics and energetics of charge repopulation, polarization, densification and localization forms the effective means engineering bonds and electrons towards devising
functional materials.
12.2 Limitations and Precautions
In using this set of BOLS-NEP notion and the APECS and ZPS strategies, the following precautions are necessary to ensure the accuracy and reliability in determining
the local bond relaxation and electronic BE shift:
(1) The CLS is proportional to the sum of the exchange and the overlap integrals
in the TB approach. The contribution of the overlap integral is 3% or less that
of the exchange integral, particularly for the deeper core levels. Involving such
overlap integral may improve the numerical accuracy of determination but it
is more complicated.
(2) Unlike the core band of a particular element, the valence band is more complicated and it includes the convoluted features of charge transport between
constituent elements in alloy or compound. The resultant valence DOS shows
states of bonding, nonbonding, holes, and antibonding dipoles.
12 Perspectives
(6) Defect formation improves the photocatalytic ability of TiO 2 by band
gap and workfunction reduction and carrier life extension through the
undercoordination-induced quantum entrapment and polarization—pining
dipoles. Transition from entrapment to polarization dominance occurs at a
critical size or surface curvasture.
(7) Water is the simplest among the molecular crystals as it contains equal number of
dangling protons and lone pairs. Lone pair and dangling proton are the primary
functional and structural units of molecular crystals. Molecular undercoordoination and electrostatic polarization shorten the H–O bond and lengthen the O:H
nonbond associated with strong polarization, which leads to a supersolid phase
that is elastoviscus, hydrophobic, less dense, mechanically and thermally more
stable. The supersolidity disperses the quansisolid phase boundaries to raise the
melting temperature and lowers the freezing point and evaporation of water ice.
(8) Spin-resolved polarization by atomic undercoordination and sp-orbital
hybridization could reconcile the skin and monolayer high-T C superconductivity and topological insulator edge superconductivity. The strength of spin-spin
coupling determines the T C and the conduction bandgap width; the localized
polarization determines the edge or skin paths of carrier travelling.
Findings not only demonstrate the power of the BOLS-NEP-ZPS and the APECS
strategies in complementing STM/S and PES but also the essentiality of the perspective of bonding and electronic dynamics associated with irregular atomic and
molecular coordination and orbital hybridization. Controlling the process of bond
and nonbond formation, dissociation, vibration, and relaxation and the associated
dynamics and energetics of charge repopulation, polarization, densification and localization forms the effective means engineering bonds and electrons towards devising
functional materials.
12.2 Limitations and Precautions
In using this set of BOLS-NEP notion and the APECS and ZPS strategies, the following precautions are necessary to ensure the accuracy and reliability in determining
the local bond relaxation and electronic BE shift:
(1) The CLS is proportional to the sum of the exchange and the overlap integrals
in the TB approach. The contribution of the overlap integral is 3% or less that
of the exchange integral, particularly for the deeper core levels. Involving such
overlap integral may improve the numerical accuracy of determination but it
is more complicated.
(2) Unlike the core band of a particular element, the valence band is more complicated and it includes the convoluted features of charge transport between
constituent elements in alloy or compound. The resultant valence DOS shows
states of bonding, nonbonding, holes, and antibonding dipoles.