Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Zeros defined

Equation (5.21) is based on the electrochemical way of counting the energy difference between zero (defined throughout this book as the potential energy of an electron at its ground state at "infinite" distance from the metal) and the Fermi level Ep (Eq. 5.15). The latter quantity must not be confused with the Fermi energy go which is the energy difference between... [Pg.213]

Nishi, et al. [ ] then find the value of B at which R(B) becomes zero, defined as the critical wave number, B ... [Pg.288]

Molecular orbitals will be very irregular three-dimensional functions with maxima near the nuclei since the electrons are most likely to be found there and falling off toward zero as the distance from the nuclei increases. There will also be many zeros defining nodal surfaces that separate phase changes. These requirements are satisfied by a linear combination of atom-centered basis functions. The basis functions we choose should describe as closely as possible the correct distribution of electrons in the vicinity of nuclei since, when the electron is close to one atom and far from the others, its distribution will resemble an AO of that atom. And yet they should be simple enough that mathematical operations required in the solution of the Fock equations can actually be carried out efficiently. The first requirement is easily satisfied by choosing hydrogenic AOs as a basis... [Pg.24]

No elements are listed in Table 8.2 because, by definition, the most stable form of any element in its standard state has AH°f = 0 kj. (That is, the enthalpy change for formation of an element from itself is zero.) Defining AH°f as zero for all elements thus establishes a kind of thermochemical "sea level," or reference point, from which all enthalpy changes are measured. [Pg.317]

Figure 3.30 Structure of ABPAC, a 9-aryl, 10-methyl derivative of the acrdinium cation, where the aryl group is 4 -amino-4-biphenylyl. The dihedral angles associated with the single bonds linking the phenyl groups are labeled 03 (phenyl/acridinium) and 02 (the biphenylyl moiety), with zero defined by coplanarity (as drawn). For the aminophenyl linkage (NC), 01 refers to the dihedral angle between the HNC and NCC planes associated with the HNCC bonded sequence. The optimized H2N moiety is pyramidalized, and is nearly symmetrically disposed with respect to the mean plane of the attached phenyl group (with 01 = 17°) [29]. Figure 3.30 Structure of ABPAC, a 9-aryl, 10-methyl derivative of the acrdinium cation, where the aryl group is 4 -amino-4-biphenylyl. The dihedral angles associated with the single bonds linking the phenyl groups are labeled 03 (phenyl/acridinium) and 02 (the biphenylyl moiety), with zero defined by coplanarity (as drawn). For the aminophenyl linkage (NC), 01 refers to the dihedral angle between the HNC and NCC planes associated with the HNCC bonded sequence. The optimized H2N moiety is pyramidalized, and is nearly symmetrically disposed with respect to the mean plane of the attached phenyl group (with 01 = 17°) [29].
Equations 15 and 17 constitute a homogeneous system of 2N + 2 linear equations. A nontrivial solution for the set of amplitudes only exists if the determinant of this equation system vanishes. The search for the zeros of the determinant as a function of frequency will in general be carried out numerically. The zeros define the resonance frequencies. Since, for a real material, the shear modulus always contains a dissipative component, G", the resonance frequencies are complex (where the imaginary part is the halfband-half-width, r). [Pg.62]

The distance, at which this difference varies from zero, defines the range of correlation. In the case of a simultaneous interaction among three atoms, the probability of their existence in spatce elements dVi, dVi, dVj at distances ri, ft, fa is defined by a ternary distribution function. 7 3(ri,r2,r3) ... [Pg.166]

The function j dlUo a,T), whose zeroes define the extremal wavelet contributions, has its smallest scale, extremal value, at oq(t). Examination of the function d Uoia, r), as o is varied from the infinite regime to the small scale value, a — 0(.l), shows that it varies slowly and then begins to decay more rapidly starting at oq(t). All of these scales are noted in Tables 5-7. [Pg.243]

The pol)mer concentration at which the permeate flux is zero, defined as gel point concentration, was found to be 655-665 mM (approximately 5.98-6.07 wt%). These values allow high water recoveries (higher than 99%) to be obtained. An advantage of the PEUF system in the... [Pg.89]

Figure 9. Pulsed photon antibunching experiment, (a) The continuous wave (cw) excitation source from figure 8 is replaced by a short-pulsed laser (pulse length much shorter than the fluorescence lifetime), (b) Molecules are now excited at well-defined times rather than randomly, resulting in peaks in the photon pair arrival histogram. If single molecules are addressed, the peak at time zero (defined by the delay length) is suppressed. Figure 9. Pulsed photon antibunching experiment, (a) The continuous wave (cw) excitation source from figure 8 is replaced by a short-pulsed laser (pulse length much shorter than the fluorescence lifetime), (b) Molecules are now excited at well-defined times rather than randomly, resulting in peaks in the photon pair arrival histogram. If single molecules are addressed, the peak at time zero (defined by the delay length) is suppressed.
A common reference energy level, the so-called crystal zero, can be uniquely defined for both electrons and positrons in perfect solids. Therefore, the energy levels in the calculations are measured relative to this internal quantity. The electron chemical potential p- is defined as the distance of the Fermi levels from the crystal zero (see Figure 4.33). Similarly, the distance of the lowest positron energy level from the crystal zero defines the positron chemical potential p,+ (Figure 4.32). [Pg.90]

It is necessary to assume that the medium is isotropic, uniform, randomly constructed and represented by a nore-throat geometry between its boundaries. Connectivity of 1 implies a poorly connected or dead-ended pore connectivity of zero defines an isolated pore. Parallel, non-intersecting pores would define a one dimension void space of connectivity 2. Time effects due to intrapatticle back-mixing would create an extra dimension and lead to dynamic sensitivity of apparent transport resistance. [Pg.201]


See other pages where Zeros defined is mentioned: [Pg.358]    [Pg.358]    [Pg.187]    [Pg.25]    [Pg.25]    [Pg.164]    [Pg.24]    [Pg.442]    [Pg.254]    [Pg.24]    [Pg.664]    [Pg.143]    [Pg.487]    [Pg.24]    [Pg.78]    [Pg.461]    [Pg.358]    [Pg.124]    [Pg.30]    [Pg.87]    [Pg.147]    [Pg.276]    [Pg.305]    [Pg.87]    [Pg.360]    [Pg.284]    [Pg.286]    [Pg.143]    [Pg.236]    [Pg.192]   
See also in sourсe #XX -- [ Pg.196 ]




SEARCH



Absolute zero, defined

© 2024 chempedia.info