Big Chemical Encyclopedia

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

Articles Figures Tables About

SOME ADDITIONAL CALCULATIONS

Because of the coupling Hamiltonian Hqm/mm, some additional calculations are needed. Of course, the terms which do not involve electron coordinates are not included in QM calculations (such as the Van der Waals terms). They are calculated outside the quemtum calculation procedure and added directly to the energy term. Therefore, the final forms of the additional integrals that need to be calculated are ... [Pg.108]

Some additional calculations were performed for comparison sake, using as a criterion the RMS error of spectral reconstruction. In particular, each spectrum was compressed to the degree which allows it reconstruction with the RMS = 0.0127. This value corresponds to the mean value of RMS observed for the data compressed by PCA. or in the joint basis accounting for the 99% of data variance. DWT with RMS criterion (where RMS = 0.0127) leads to 66.8 wavelet coefficients. For illustrative purpose the original spectrum and the spectrum reconstructed with RMS = 0.0127 are presented in Fig. 6. [Pg.299]

STENSLAND That is a possibility. I think I have seen a comment in the literature where the magnitude of that source was estimated to be relatively unimportant, but I should do some additional calculations concerning this source. With all the farmland being brown so many months of the year, this is the first source that I consider. Also I did not mention gravel roads. If we had a lot more gravel roads in the fifties compared to now, then this is possibly another importaint source to be thinking about. [Pg.108]

Most calculations were run on the CRUNTCh (Computational Research at UNT in Chemistry) Linux farm at the University of North Texas, on the high-performance computing National Computational Infrastructure (NCI) National Facility at Canberra, and on the iVEC UWA facilities. Some additional calculations were carried out on the Faculty of Chemistry Linux farm at the Weizmann Institute of Science. [Pg.245]

Some additional calculation steps required for the regression are ... [Pg.406]

Section 9 of Volume 1 of the Hazards Review contains a discussion of the consequences of a partial and total meltdown of the N Reactor fuel core. Estimates of areas were presented within which various levels of exposure and contamination could be expected. The purpose of this Appendix Is to present material supporting the calculations and to present results of some additional calculations perfoaned since Volume 1 was published. [Pg.371]

Next determine the rich amine solution temperature exiting the contactor, Tr. by an enthalpy balance around the contactor. To simplify the calculations, as previously discussed, use the feed gas temperature, Tp, as the reference temperature. However, before this balance can be completed, it is necessary to make some additional calculations ... [Pg.140]

The program system COBRA [118, 119] can be regarded as a rule- and data-based approach, but also applies the principles of fragment-based (or template-based) methods extensively (for a detailed description sec Chapter 11, Sections 7.1 and 7.2 in the Handbook). COBRA uses a library of predefined, optimized 3D molecular fragments which have been derived from crystal structures and foi ce-field calculations. Each fi agment contains some additional information on... [Pg.98]

The forces are calculated as part of a molecular dynamics simulation, cind so little additional effort is required to calculate the virial and thus the pressure. The forces are not routinely calculated during a Monte Carlo simulation, and so some additional effort is required to determine the pressure by this route. When calculating the pressure it is also important to check that the components of the pressure in all three directions are equal. [Pg.323]

The optimization of a transition structure will be much faster using methods for which the Hessian can be analytically calculated. For methods that incrementally compute the Hessian (i.e., the Berny algorithm), it is fastest to start with a Hessian from some simpler calculation, such as a semiempirical calculation. Occasionally, dilficulties are encountered due to these simpler methods giving a poor description of the Hessian. An option to compute the initial Hessian at the desired level of theory is often available to circumvent this problem at the expense of additional CPU time. [Pg.152]

Many semiempirical methods have been created for modeling organic compounds. These methods correctly predict many aspects of electronic structure, such as aromaticity. Furthermore, these orbital-based methods give additional information about the compounds, such as population analysis. There are also good techniques for including solvation elfects in some semiempirical calculations. Semiempirical methods are discussed further in Chapter 4. [Pg.284]

If the r-value falls short of the formal significance level, this is not to be interpreted as proving the absence of a systematic error. Perhaps the data were insufficient in precision or in number to establish the presence of a constant error. Especially when the calculated value for t is only slightly short of the tabulated value, some additional data may suffice to build up the evidence for a constant error (or the lack thereof). [Pg.199]

MP4(SDQ)/6-31+(d,p) calculation is used to approximate higher order contributions. This model also includes some additional empirical corrections. [Pg.156]

In the next section we describe a very simple model, which we shall term the crystalline model , which is taken to represent the real, complicated crystal. Some additional, more physical, properties are included in the later calculations of the well-established theories (see Sect. 3.6 and 3.7.2), however, they are treated as perturbations about this basic model, and depend upon its being a good first approximation. Then, Sect. 2.1 deals with the information which one would hope to obtain from equilibrium crystals — this includes bulk and surface properties and their relationship to a crystal s melting temperature. Even here, using only thermodynamic arguments, there is no common line of approach to the interpretation of the data, yet this fundamental problem does not appear to have received the attention it warrants. The concluding section of this chapter summarizes and contrasts some further assumptions made about the model, which then lead to the various growth theories. The details of the way in which these assumptions are applied will be dealt with in Sects. 3 and 4. [Pg.226]

Equations 4.55 and 4.57 are the most convenient for the calculation of gas flowrate as a function of Pi and Pi under isothermal conditions. Some additional refinement can be added if a compressibility factor is introduced as defined by the relation Pv -= ZRT/M, for conditions where there are significant deviations from the ideal gas law (equation 2.15). [Pg.161]

In the semiclassical centrifugal sudden (SCS) approximation some additional simplifications were made, which permit us to estimate the scattering phase by Eq. (5.50). Therefore the accuracy of SCS has to be checked separately. Fortunately, for the Ar-N2 system some cross-sections were calculated by the BFCP method [200] as well as by the CC method [206], which is considered to be the best. Using the same potential as in [209] the SCS cross-sections were found in [191] for fixed total energy of collisions E. The results are compared in Table 5.1. [Pg.170]

In addition to these interactions, one must take into account that reorganization of the solvent molecules requires the expenditure of some energy Calculations show that this energy for water has values of -60 to -120kJ/mol. [Pg.110]

The preceding calculations can also be performed for finite cavity sizes. For this case, there are some additional sources of small amounts of energy associated with cavity formation arising from surface tension, pressure-volume work, and electrostriction. Because of the Franck-Condon principle these do not affect the transition energy, but they have some influence on the heat of solvation. Jortner s (1964) results are summarized as follows ... [Pg.171]

Calculations have proven invaluable in understanding the many differences between la and lb. In addition, calculations have provided insight into the substituent effects on the ring expansion reactions of derivatives of lb. Finally, calculations have made predictions about the barriers to and regiochemistries of these reactions. Some of these predictions have been verified others await experimental test. [Pg.247]

There is a routine procedure to form the transport pores in catalysts catalyst is mixed with some additive, which can be burned off after preparation. Consider the catalyst with true density pc = 3.3 g/cm3 and the additive (carbon black) with true density of pA= 1.2 g/cm3. Calculate the amount of additive necessary to form the interlinked system of transport pores. [Pg.336]

All calculations were performed using Gaussian98 [77], which required making some additions and corrections to the UFF force field because Gaussian98 does not have atom types for square planar rhodium or coordinated double bonds. Details about these changes can be found in the supporting information of our original paper [72],... [Pg.120]

SAM-coated and clean substrates can easily reach 20 j,C/cm, which means that a simple coverage calculation from charge associated with the desorption wave is flawed, as pointed out by Schneider and Buttry [137]. In this context it is worth noting that the diflerence in capacity between SAM-coated and dean electrodes is not only due to the introduction of a dielectric layer but depends also on the surface of the SAM and its interaction with the environment, that is, whether the surface exhibits some additional charges either due to ionic tail groups or due to speciflc interaction of the SAM with the electrolyte. [Pg.213]

Some additional noteworthy features of the calculated results shown in Figures 3 and 4 are as follows. [Pg.278]


See other pages where SOME ADDITIONAL CALCULATIONS is mentioned: [Pg.254]    [Pg.301]    [Pg.307]    [Pg.313]    [Pg.355]    [Pg.99]    [Pg.304]    [Pg.237]    [Pg.254]    [Pg.301]    [Pg.307]    [Pg.313]    [Pg.355]    [Pg.99]    [Pg.304]    [Pg.237]    [Pg.17]    [Pg.143]    [Pg.245]    [Pg.285]    [Pg.1120]    [Pg.108]    [Pg.313]    [Pg.142]    [Pg.209]    [Pg.177]    [Pg.563]    [Pg.226]    [Pg.630]    [Pg.147]    [Pg.78]    [Pg.155]    [Pg.629]    [Pg.243]   


SEARCH



Additivity calculation

© 2024 chempedia.info