Conventional integral evaluation

The program can use conventional, in-core, or direct integral evaluation. The default ah initio algorithm checks the disk space and memory available. It then uses an in-core method if sufficient memory is available. If memory is not available for in core evaluation, the program uses a conventional method if... 

Cools, N., De Pauw, E. and Deckers, J. 2003. Towards an integration of conventional land evaluation methods and farmers soil suitability assessment a case study in northwestern Syria. Agriculture, Ecosystems and Environment 95(1) 327-342. 

The above discussion refers especially to SCF or DFT calculations where the integral evaluation is the dominant step. This is different in MP2 (RI or conventional) or AOFORCE calculations since here it is the further processing of integrals or the storage of intermediate quantities which becomes the bottleneck. In these cases it is most efficient to optimize the integral processing with respect to CPU time and disc requirements, even if the integrals have to be computed several times. 

Evaluate the integrals. In a conventional algorithm, they are stored on disk and read in for each iteration. In a direct algorithm, integrals are computed a few at a time as the Fock matrix is formed. 

In order to allow for back scattering and plasmon scattering in the sample to be evaluated directly from the spectrum, / in equation (4) is conventionally replaced by /0((3A), the integral in the energy window under the zero-loss peak, for the acceptance angle (3. This permits the calculation of the absolute number of atoms which contributed to the edge. 

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