Big Chemical Encyclopedia

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

Articles Figures Tables About

Contraction error

As in Section IV.A. the eigenvalues of the 1-RDM must lie in the interval [0,1] with the trace of each block equal to N/2. Similarly, with the a/a- and the jS/jS-blocks of the 2-RDM being equal, only one of these blocks requires purification. The purification of either block is the same as in Section IV.B.2 with the normalization being N N/2 — l)/4. The unitary decomposition ensures that the a/a-block of the 2-RDM contracts to the a-component of the 1-RDM. The purification of Section IV.B.2, however, cannot be directly applied to the a/jS-block of the 2-RDM since the spatial orbitals are not antisymmetric for example, the element with upper indices a, i fi, i is not necessarily zero. One possibility is to apply the purification to the entire 2-RDM. While this procedure ensures that the whole 2-RDM contracts correctly to the 1-RDM, it does not generally produce a 2-RDM whose individual spin blocks contract correctly. Usually the overall 1-RDM is correct only because the a/a-spin block has a contraction error that cancels with the contraction error from the a/ S-spin block. [Pg.191]

Failure costs rework and bad planning, nonproductive times by errors in production, time to examine the causes and consequences of failures, lack of work and accidents, obsolete resources, deficient utilization of resources and external services, delays of supplies, inefficient communication and affections in computer systems, contract errors, bhhng errors, loss of income, imcollectable debt, discounts of fees, customer complaints, time consumed in internal complaints and solving the problem escalated by customer, penalties, loss of market and company reputation. [Pg.1020]

Completely uncontracting the primitive basis set leads to rather large basis sets especially for heavier systems. We have had considerable success only partially uncontracting the basis sets. For example, to derive basis sets for describing Is correlation for the first row systems we proceeded as follows. The outer s primitives describing the Is orbital are uncontracted. We usually try to obtain a triple zeta description of the Is orbital. To minimize the contraction error we frequently retain the (contracted) inner part of the 2s orbital. (We find... [Pg.585]

Quality Audit. Another important responsibiUty of quahty assurance is the audit function. Using the quahty audit as a tool, QA can monitor the operation of the manufacturing faciUty a toU, ie, contract, manufacturer or raw material suppHer to assure that written procedures are in place and that there is documentation to indicate the procedures are being followed. Properly executed audits allow QA to spot potential weakness in the quahty system that could allow errors to occur. Once identified, these weaknesses can then be corrected before they result in nonconformance. [Pg.371]

If utilities are supplied to the new project from some other source, the cost and amount must be determined. If purchased from a second party, the cost will be determined by contract and can be estimated by discussions with the vendor. If utilities are transferred from an affiliated source, the cost must include a profit to the supplying entity. Some estimators use a lower return on utility plants than on a new hydrocarbon processing unit, since the utility can be used for some alternate plant if the new one shuts down for any reason. However, the preferred analysis allows a high enough utility transfer price to provide the same return on the utilities as the new unit being studied. This can require a trial and error approach, especially if the utilities are a significant part of the selling price of the product. [Pg.239]

It becomes apparent, the farther the test gas parameter deviates from those of the contract gas, the more difficult the correlation. This leads to tesi error. [Pg.420]

When prepanng mobile phase mixtures each individual component should be measured out separately and only then placed in the mixing vessel This prevents not only contamination of the solvent stock by vapors from the already partially filled mixing vessel (e g ammonia ) but also volumetnc errors caused by volume expansions or contractions on mixing... [Pg.132]

Regarding current ab initio calculations it is probably fair to say that they are not really ab initio in every respect since they incorporate many empirical parameters. For example, a standard HF/6-31G calculation would generally be called "ab initio", but all the exponents and contraction coefficients in the basis set are selected by fitting to experimental data. Some say that this feature is one of the main reasons for the success of the Pople basis sets. Because they have been fit to real data these basis sets, not surprisingly, are good at reproducing real data. This is said to occur because the basis set incorporates systematical errors that to a large extent cancel the systematical errors in the Hartree-Fock approach. These features are of course not limited to the Pople sets. Any basis set with fixed exponent and/or contraction coefficients have at some point been adjusted to fit some data. Clearly it becomes rather difficult to demarcate sharply between so-called ab initio and semi-empirical methods.4... [Pg.96]

Magnitudes of n have been empirically established for those kinetic expressions which have found most extensive application e.g. values of n for diffusion-limited equations are usually between 0.53 and 0.58, for the contracting area and volume relations are 1.08 and 1.04, respectively and for the Avrami—Erofe ev equation [eqn. (6)] are 2.00, 3.00 etc. The most significant problem in the use of this approach is in making an accurate allowance for any error in the measured induction period since variations in t [i.e. (f + f0)] can introduce large influences upon the initial shape of the plot. Care is needed in estimating the time required for the sample to reach reaction temperature, particularly in deceleratory reactions, and in considering the influences of an induction period and/or an initial preliminary reaction. [Pg.78]

Thus the rather easily obtained atomic sizes are the best indicator of what the f-electrons are doing. It has been noted that for all metallic compounds in the literature where an f-band is believed not to occur, that the lanthanide and actinide lattice parameters appear to be identical within experimental error (12). This actually raises the question as to why the lanthanide and actinide contractions (no f-bands) for the pure elements are different. Analogies to the compounds and to the identical sizes of the 4d- and 5d- electron metals would suggest otherwise. The useful point here is that since the 4f- and 5f-compounds have the same lattice parameters when f-bands are not present, it simplifies following the systematics and clearly demonstrates that actinides are worthy of that name. [Pg.75]

Of all the requirements that have to be fulfilled by a manufacturer, starting with responsibilities and reporting relationships, warehousing practices, service contract policies, airhandUng equipment, etc., only a few of those will be touched upon here that directly relate to the analytical laboratory. Key phrases are underlined or are in italics Acceptance Criteria, Accuracy, Baseline, Calibration, Concentration range. Control samples. Data Clean-Up, Deviation, Error propagation. Error recovery. Interference, Linearity, Noise, Numerical artifact. Precision, Recovery, Reliability, Repeatability, Reproducibility, Ruggedness, Selectivity, Specifications, System Suitability, Validation. [Pg.138]

For preparation of solvent mixtures, the single solvents should be measured out separately and then properly mixed in a vessel with a ground glass stopper (avoidance of volume contraction and measuring errors). [Pg.120]

The volume profiles for the ligand substitutions on [Pd(H20)4]2+, shown in Fig. 12, exhibit an overall contraction in the transition state (AVfi) as DMSO substitutes for H20, a smaller one as MeCN substitutes, and a yet smaller one as water substitutes. The three negative AV values are identical within experimental error and also indicate a contraction to the transition state. It is particularly interesting that the difference in volume between the transition state and the reactants is independent of the leaving ligand when the entering ligand is water. Release of either DMSO or MeCN into bulk solution would produce a... [Pg.57]


See other pages where Contraction error is mentioned: [Pg.288]    [Pg.358]    [Pg.364]    [Pg.164]    [Pg.36]    [Pg.28]    [Pg.294]    [Pg.585]    [Pg.379]    [Pg.188]    [Pg.317]    [Pg.288]    [Pg.358]    [Pg.364]    [Pg.164]    [Pg.36]    [Pg.28]    [Pg.294]    [Pg.585]    [Pg.379]    [Pg.188]    [Pg.317]    [Pg.142]    [Pg.236]    [Pg.38]    [Pg.38]    [Pg.651]    [Pg.470]    [Pg.420]    [Pg.162]    [Pg.163]    [Pg.216]    [Pg.290]    [Pg.1081]    [Pg.81]    [Pg.193]    [Pg.122]    [Pg.149]    [Pg.614]    [Pg.16]    [Pg.1035]    [Pg.120]    [Pg.137]    [Pg.145]   
See also in sourсe #XX -- [ Pg.28 ]




SEARCH



© 2024 chempedia.info