Benchmark computers

As auxiliary RI correlation consistent basis sets have been optimized, an RI-ccCA implementation was created by Prascher and Wilson [154], replacing all MP2 steps with their equivalent RI-MP2 computations, and the CCSD(T)-additive correction with the local RI-CCSD(T) method developed by Schiitz and Werner [159-161]. Correlation consistent auxiliary basis sets developed by Weigend [162] were utilized for the various ccCA steps. Benchmark computations on 102 closed... 

Abstract The modified equation-of-motion coupled cluster approach of Sekino and Bartlett is extended to computations of the mixed electric-dipole/magnetic-dipole polarizability tensor associated with optical rotation in chiral systems. The approach - referred to here as a linearized equation-of-motion coupled cluster (EOM-CCl) method - is a compromise between the standard EOM method and its linear response counterpart, which avoids the evaluation of computationally expensive terms that are quadratic in the field-perturbed wave functions, but still yields properties that are size-extensive/intensive. Benchmark computations on five representative chiral molecules, including (P)-hydrogen peroxide, (5)-methyloxirane, (5 )-2-chloropropioniuile, (/ )-epichlorohydrin, and (75,45)-norbornenone, demonstrate typically small deviations between the EOM-CCl results and those from coupled cluster linear response theory, and no variation in the signs of the predicted rotations. In addition, the EOM-CCl approach is found to reduce the overall computing time for multi-wavelength-specific rotation computations by up to 34%. 

The requirements of ANSI/ANS 8.1 specify that calculational methods for away-from-reactor criticality safety analyses be validated against experimental measurements. If credit is to be taken for the reduced reactivity of burned or spent fuel relative to its original fresh composition, it is necessary to benchmark computational methods used in determining such reactivity worth against spent fuel reactivity measurements. This report summarizes a portion of the ongoing effort to benchmark away-from-reactor criticality analysis methods using critical configurations from commercial pressurized- water reactors (PWR). 

Design methods based on test results are particularly appropriate for loads in design basis external human induced events, on account of the wide spread of response predictions observed in non-linear numerical analyses not using benchmarked computer solutions. However, extreme care should be taken when empirical or semi-empirical approaches are employed outside the range of parameters of the corresponding database. 

Hysing, S., Turek, S., Kuzmin, D., Parolini, N., Burman, E., Ganesan, S., et al. (2009). Quantitative benchmark computations of two-dimensional bubble dynamics. International Journal for Numerical Methods inFluids, 60, 1259-1288. doi 10.1002/fld.l934. 

D incompressible two-phase flow benchmark computations for rising droplets [online], [cit 2014-03-01]. Retrieved from http //wissrech.ms.uni-bonn.de/research/projects/ risingbubblebenchmark/... 

The direct visualization of the flow behavior inside of the mould cavity under processing conditions close to industrial set-ups can be used for experimental investigation with several aims. The main one is to have direct access to the details of the flow patterns developed under different processing conditions. Visualization is also used to benchmark computer modeling codes, namely of filling and holding stages. 

Fig. 3. Average computation time for one step using EGO.VIII on a DEC-Alpha 3300L workstation (175 MHz) for simulation systems of varying size. The insets show some of the protein-water systems used for the benchmark simulations.

The program can be run either in a serial or parallel execution mode. Both execution modes were stable when tested on a multiprocessor Linux system. Parallel calculations can be run either on parallel computers or networked workstations. Benchmark information is available at the website listed below. 

In Table 2, the computers ia the MOPAC benchmark are grouped as they are to reflect differing floatiag-poiat machine represeatatioas. AH these computers use 64 bits to represeat a double precisioa floatiag-poiat aumber. Differeat behavior arises from the slightly differeat ways ia which the bits are allocated. 

This decreasing efficiency is a general characteristic of shared memory, shared bus computers. This example shows unusually high efficiency compared with many other programs. This may be because LINPACK is such a common benchmark that much effort has been devoted to optimising it for both vector and parallel computers. 

Hyperfine coupling constants provide a direct experimental measure of the distribution of unpaired spin density in paramagnetic molecules and can serve as a critical benchmark for electronic wave functions [1,2], Conversely, given an accurate theoretical model, one can obtain considerable information on the equilibrium stmcture of a free radical from the computed hyperfine coupling constants and from their dependenee on temperature. In this scenario, proper account of vibrational modulation effects is not less important than the use of a high quality electronic wave function. 

AuH and Au2 serve as benchmark molecules to test the performance of various relativistic approximations. Figure 4.7 shows predictions for relativistic bond contractions of Au2 from various quantum chemical calculations over more than a decade. In the early years of relativistic quantum chemistry these predictions varied significantly (between 0.2 and 0.3 A), but as the methods and algorithms became more refined, and the computers more powerful, the relativistic bond contraction for Au2 converged and is now at 0.26 A. 

Finally, we should mention that experimental data serving as a benchmark for the appraisal of computational methods must be highly accurate. Setting the goal of 2 kcal/mol for useful accuracy of calculated thermochemical data means of course, that a still better level of accuracy must be reached by experimental measurements. The high accuracy of... 

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