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Charge, atomic

The charge attributed to an atom A within a molecule, defined as = Za — where Za is the atomic number of atom A and A is the electron density (see Atoms in Molecules) assigned to A. The calculation of q depends on the partitioning of the electron density. In the framework of Mulliken population analysis (see Electronic Wavefunctions Analysis), cja is related to the gross atomic population H q, where q is the gross [Pg.63]


Momany F A 1978 Determination of partial atomic charges from ab initio molecular electrostatic potentials. Application to formamide, methanol and formic acid J. Phys. Chem. 82 592... [Pg.216]

Wberg K B and Rablen P R 1993 Comparison of atomic charges by different procedures J. Comput. Chem. 14 1504... [Pg.216]

The solvent dielectric constant, ionic strength and temperature are chosen to fit the conditions of the experimental studies. The protein dielectric constant is assigned some small value, e.g. 4. The PB calculations are currently carried out with the atomic charges and radii of the PARSE parameter set, developed by Honig and coworkers [17] or that for CHARMM [12]. The PARSE parameter set... [Pg.182]

Molecular surfaces can express various chemical and physical properties, such as electrostatic potential, atomic charges or hydrophobicity, using colored mapping. [Pg.160]

Two other atomic properties have been used in the definition of atom type, thereby increasing its fuzziness relative to that in the ap and tt descriptors - atomic log P contribution (yielding hydrophobic pairs, hps, and torsions, hts) and partial atomic charges (charge pairs, cps, and charge torsions, cts). [Pg.311]

The authors emphasize on their web pages that UFF is not designed to be used in conjunction with partial atomic charges, as it is the default option in several software packages. A second point is that UFF is often used to model biological... [Pg.350]

Many problems in force field investigations arise from the calculation of Coulomb interactions with fixed charges, thereby neglecting possible mutual polarization. With that obvious drawback in mind, Ulrich Sternberg developed the COSMOS (Computer Simulation of Molecular Structures) force field [30], which extends a classical molecular mechanics force field by serai-empirical charge calculation based on bond polarization theory [31, 32]. This approach has the advantage that the atomic charges depend on the three-dimensional structure of the molecule. Parts of the functional form of COSMOS were taken from the PIMM force field of Lindner et al., which combines self-consistent field theory for r-orbitals ( nr-SCF) with molecular mechanics [33, 34]. [Pg.351]

The MEP at the molecular surface has been used for many QSAR and QSPR applications. Quantum mechanically calculated MEPs are more detailed and accurate at the important areas of the surface than those derived from net atomic charges and are therefore usually preferable [Ij. However, any of the techniques based on MEPs calculated from net atomic charges can be used for full quantum mechanical calculations, and vice versa. The best-known descriptors based on the statistics of the MEP at the molecular surface are those introduced by Murray and Politzer [44]. These were originally formulated for DFT calculations using an isodensity surface. They have also been used very extensively with semi-empirical MO techniques and solvent-accessible surfaces [1, 2]. The charged polar surface area (CPSA) descriptors proposed by Stanton and Jurs [45] are also based on charges derived from semi-empirical MO calculations. [Pg.393]

A range of physicochemical properties such as partial atomic charges [9] or measures of the polarizabihty [10] can be calculated, for example with the program package PETRA [11]. The topological autocorrelation vector is invariant with respect to translation, rotation, and the conformer of the molecule considered. An alignment of molecules is not necessary for the calculation of their autocorrelation vectors. [Pg.411]

The chirality code of a molecule is based on atomic properties and on the 3D structure. Examples of atomic properties arc partial atomic charges and polarizabilities, which are easily accessible by fast empirical methods contained in the PETRA package. Other atomic properties, calculated by other methods, can in principle be used. It is convenient, however, if the chosen atomic property discriminates as much as possible between non-equivalent atoms. 3D molecular structures are easily generated by the GORINA software package (see Section 2.13), but other sources of 3D structures can be used as well. [Pg.420]

Figure 8-11. iD structure and representation offcoccia) versus u for (fi)-4 and [S)-4 at two different conformations (a and b) sampled at 50 evenly separated values between -0,100 e A and i-0.100 e A. Partial atomic charge was used as the atomic property. [Pg.425]

Quantum chemical descriptors such as atomic charges, HOMO and LUMO energies, HOMO and LUMO orbital energy differences, atom-atom polarizabilities, super-delocalizabilities, molecular polarizabilities, dipole moments, and energies sucb as the beat of formation, ionization potential, electron affinity, and energy of protonation are applicable in QSAR/QSPR studies. A review is given by Karelson et al. [45]. [Pg.427]

UvHV tff cctivc Diameter V Potential of positive atomic charges... [Pg.508]

An extended set of physicochemical descriptors was used in this study, including, for example, partial atomic charge and effective polari2 ability of the protons, average of electronegativities of atoms two bonds away, or maximum, T-atomic charge of atoms two bonds away. [Pg.525]

In Eq. (16 i denotes an atom up to lour non-rotatable bonds away from the proton and is the total number of those atoms. A bond is deRned as non-rotatable if it belongs to a ring, to a. T-system, or to an amide functional group q- is the partial atomic charge of the atom i, and is the 3D distance between the proton j and the atom i. Figure 10.2-5 shows an example of a proton RDF descriptor. [Pg.525]

Despite th ese reservation s. Mu Ilikeri population -derived atomic charges arc easy to compute. Empirical investigation shows that they have various uses, they provide approximate representation of the 3D charge distribution within a molecule. [Pg.138]

AMBER. BlO-t-. and OPLS calciilations use information on atomic charges. Atomic charges can come from these sources ... [Pg.138]


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AIM atomic charges

Accuracy atomic charges

Alcohols atomic charges

Aldehydes atomic charges

Alkanes atomic charges

Amines Charges of the Carbon Atoms

Analytical gradients Atomic charges

Aromatic hydrocarbons atomic charges

Aromaticity bond orbital atomic charges

Atom and charged dimer formation

Atom charge superposition

Atom-centered charges

Atom-centered point charges

Atomic Charges, Bond Properties, and Molecular Energies, by Sandor Fliszar

Atomic charge Bader QTAIM

Atomic charge densities

Atomic charge difference parameter

Atomic charge dipole-fitting

Atomic charge distribution

Atomic charge distribution for the

Atomic charge model

Atomic charge physical quantity

Atomic charge population

Atomic charges Hilbert space partitioning

Atomic charges Mulliken-type analysis

Atomic charges RESP)

Atomic charges ambiguity

Atomic charges and NMR shifts

Atomic charges and charge flux

Atomic charges carbonyl halides

Atomic charges definition

Atomic charges electrostatic

Atomic charges force related

Atomic charges from different models

Atomic charges molecular mechanics schemes

Atomic charges parameters

Atomic charges potential

Atomic charges quantum mechanical theory

Atomic charges, computational procedures

Atomic charges, dielectric constant

Atomic charges, dielectric constant electrostatic energies

Atomic complexities singly charged ions

Atomic effective charge model

Atomic partial charges acid interaction

Atomic partial charges calculation

Atomic partial charges interaction

Atomic point charge

Atomic point charge model

Atomic point-charge potential

Atomic polar tensor charges

Atomic properties partial charges

Atomic species electrical charge

Atoms and the Charge Distribution

Atoms charge stability

Atoms electric charges

Atoms formal charges

Atoms negative charges

Atoms/atomic charges

Atoms/atomic charges

Atoms: atomic number charges

Average atomic charge

Benzyl carbanion, atomic charge

CNDO/2 atomic partial charge

Carbon atom charge stability

Carbon atom with formal charge

Carbon charged atom

Carbonyl compounds atomic charges

Cationic Dyes with Sulfur or Phosphorus as Charge-Carrying Atoms

Charge atomic number and

Charge atomic spectroscopy

Charge density atom-centered expansion

Charge density helium atom

Charge number atoms

Charge of an atom

Charge on carbon atom

Charge on the ath atom

Charge transfer atomic systems

Charge transfer in neutral atom-multiply charged ion collisions

Charge transfer on an atomic scale

Charge, atomic Gasteiger-Marsili

Charge, atomic overview

Charge-transfer, heavy atoms

Charged atoms

Charged atoms

Charges atom

Charges atom

Charges on atoms in molecules

Cluster compounds atomic charge

Correlation, effects atomic charges

Density functional perturbation theory atomic charge

Determining atomic charges

Dissociation constant atomic partial charge

Effective Bond Charges from Rotation-Free Atomic Polar Tensors

Effective Induced Bond Charges From Atomic Polarizability Tensors

Effective atomic number nuclear charge

Effective charge atomic

Effective charges of atoms

Electric charge, atomic structure

Electric charges, in atoms

Electric properties atomic charges

Electrical charge in atom

Electrical charges electrically neutral atoms

Electron atomic charges

Electronic charge around atom

Electronic distribution atomic natural charges

Ethanol Atomic charges

Ethers atomic charges

Exercise 8.4 Atomic Charge Analysis

External Heavy-Atom Effects and Charge Transfer

Factor 1—What Atom Is the Charge on

Formic acid Atomic charges

Fractional Atomic Charges

Fukui Functions and Atomic Charges

Gasteiger atomic charges

Generalized atomic polar tensor charges

Graphitized carbon atomic partial charge

Gross atomic charge

Hirshfeld atomic charge

Hydrogen atom, charge cloud model

Hypervalent molecules atomic charges

INDUCTIVE EFFECTS ATOMIC CHARGES

Ketones atomic charges

Lewis-Langmuir atomic charges

Local Density of States and Atomic Charges

Mean atom charge

Meaningful Atomic Charges

Molecular descriptors atomic partial charges

Mulliken atomic charges

Mulliken atomic partial charges

Mulliken net atomic charges

Natural Atomic Orbital-Point Charge

Natural atomic charges

Natural charging atomization process

Negative charge atom bearing

Net Charges of Transition Metal Atoms

Net atomic charges reproducing the electrostatic potential

Net atomic partial charges

Net charge of atoms

Nitrogen atom with formal charge

Nucleus The small, dense center of positive charge in an atom

Of single charged atomic ions

Off-atom charge sites

Olefins atomic charges

Oxygen atom with formal charge

Partial atomic charge

Polar Bond, Effective Charges of Atoms

Positively charged atom

Potential derived atomic charges

Proton A positively charged particle atomic nucleus

Quantitative structure-property atomic partial charges

Quantumchemical calculation, update charges on atoms

Results for Potential-Derived Net Atomic Charges

Selected Reference Net Atomic Charges

Skeletal structures with charged carbon atoms

Stewart atomic charges

Stockholder atomic charges

Subject atomic partial charge

Sulfur atoms formal charge

Surfaces atomic charges

The Molecular Electrostatic Potential and Atomic Charges

The Pluses and Minuses of Mapping Atomic Charges to Electrostatic Potentials

The estimation of net atomic charges from calculated electron densities

The resonance charge exchange in ion-atom collisions

Transferability of charge density parameters among related atoms

Voronoi atomic charges

Voronoi, Hirshfeld and Stewart atomic charges

Water atomic charge

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