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Memory requirements:

The CCSD and CCSD(T) implementation in Turbomole uses multi-pass algorithms to avoid strictly the need to store any arrays with a size of N3 or O2N2 or larger as complete array in main memory. Therefore, the minimum memory requirements are relatively low--although is difficult to give accurate estimate for them.

On should, however, be aware that, if the amount of memory provided to the program in the data group $maxcor becomes too small compared to O2N2/(128×1024) MBytes, loops will be broken in many small batches at the cost of increased I/O operations and a decrease in performance. As mentioned above, it is recommended to set $maxcor to 66-77% of the physical core memory available for the calculation.