Single Point

We can also visualise the subsurface as being made up of an enormous number of point scatterers or diffractors. (Fig b). Each contributes a diffraction curve (hyperbola) to the reflection section. Migration focuses the energy in these curves to a single point. 

The existence of this situation (for nonporous solids) explains why the ratio test discussed above and exemplified by the data in Table XVII-3 works so well. Essentially, any isotherm fitting data in the multilayer region must contain a parameter that will be found to be proportional to surface area. In fact, this observation explains the success of Ae point B method (as in Fig. XVII-7) and other single-point methods, since for any P/P value in the characteristic isotherm region, the measured n is related to the surface area of the solid by a proportionality constant that is independent of the nature of the solid. 

The free energy differences obtained from our constrained simulations refer to strictly specified states, defined by single points in the 14-dimensional dihedral space. Standard concepts of a molecular conformation include some region, or volume in that space, explored by thermal fluctuations around a transient equilibrium structure. To obtain the free energy differences between conformers of the unconstrained peptide, a correction for the thermodynamic state is needed. The volume of explored conformational space may be estimated from the covariance matrix of the coordinates of interest, = ((Ci [13, lOj. For each of the four selected conform-... 

On e type of single point calculation, that of calculating vibration al properties, is distinguished as a vihmiions calculation in Ilyper-Chein. A lufcratilrui.s calculation predicts fun dam en tal vibrational frecinencies, m frared absorption in tensities, and norm al modes for a geometry optimized molecular structure. 

Ohlaiii a new stable structure as a starting point for a single point, quantum mechanical calculation, which provides a large set ol structural and electronic properties. 

Specifies the calculation ofelectron correlation energy using the Mwllcr-i lessct second order perturbation theory (Ml 2). This option can only be applied Lo Single Point calculations. 

ZIXDO/S is parameteri/ed to reproduce spectroscopic transitions, therefore we do not recommend using this method for geometry optim i/ation. You can obtain better results by performing a single-point calculation wuth ZIXDO/S on a geometry obtained from the Model Builder, an optim Ization iisln g one of IlyperChem s oth er methods, or an external source. 

IlyperChem provides three types ofpotential energy surface sampling algorithms. These are found m the IlyperChem Compute menu Single Point, Ceometry Optimization, and Molecular Dynamics. 

Th c eigen value of ih is Sch riidiri gcr equation. the electron ie energy deperi ds parametrically, as sh own, on the coord in ales of th e nuclei (assumed to he fixed for the purposes of calcti lali ri g each Heie.lK), bin variable in general), I h e electronic energy, combined with y, (K,K) is the total energy of Single Point semi-em pirical calculation s. 

A single poinL calcnlaiion at the points b, c, d, or e will give a higher energy. E, than a single point calculation near the niini-mu ni at a. 

Ifse the electronic Spectrum dialog box to display and analyze the IfV-vis spectrum produced by a singly excitetl Cl calculation. This dialog box is available only after yon do a single point Cl semi-einpirical calculation. Electronic Spectrum is then activated on the Compute menu. 

W C, A Tempcz)rrk, R C Hawley and T Hendrickson 1990. Semianalytical Treatment of Solvation for Molecular Mechanics and Dynamics. Journal of the American Chemical Society 112 6127-6129. ensson M, S Humbel, R D J Froese, T Matsubara, S Sieber and K Morokuma 1996. ONIOM A Multilayered Integrated MO + MM Method for Geometry Optimisations and Single Point Energy Predictions. A Test for Diels-Alder Reactions and Pt(P(t-Bu)3)2 + H2 Oxidative Addition. Journal of Physical Chemistry 100 19357-19363. 

To go from a semiempirical calculation in the GAUSSIAN implementation (File 9-1) to an ab initio calculation, one need only change PM3 in the route section of the input file to sto-3g for a single point calculation or sto-3g opt for an optimization. We have made this change in File 10-1 along with the substitution of h for f in the second line of the geometry section to calculate the molecular... 

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