MaxDisk キーワードは量を指定します スクラッチ データに使用できるディスク ストレージ (8 バイト ワード) (デフォルト)。この値の後に次の値が続くこともあります KB, MB, GB, TB, KW, MW, GW または TW (スペースを挟まずに) キロ、メガ、ギガ、テラバイトまたはワードの単位を指定します。通常、これは次のサイトに設定されます。 Default.Route file.

すべての計算でディスク使用量を動的に制御できるわけではないため、このキーワードの効果は次のように異なります。

• SCF energy, gradient, と frequency calculations use a fixed amount of disk. This is quite small (only cubic in the size of the system) と is not usually a limitation.
• MP2 energies と gradients obey MaxDisk, which must be at least 2ON².
• Analytic MP2 frequencies attempt to obey MaxDisk, but have minimum disk requirements.
• CI-Singles energies と gradients in the MO basis require about 4O²N² words of disk for a limited set of transformed integrals. Additional scratch space is required during the transformation と this is limited as specified by MaxDisk. This disk requirement can be eliminated entirely by performing a direct CI-Singles calculation by using CIS=Direct.
• CID, CISD, CCD, BD, と QCISD energies also have a fixed storage requirement proportional to O²N², with a large factor, but obey MaxDisk in avoiding larger storage requirements.
• CCSD, CCSD(T), QCISD(T), と BD(T) energies have fixed disk requirements proportional to ON³ which cannot be limited by MaxDisk.
• CID, CISD, CCD, QCISD densities, と BD と CCSD densities と gradients have fixed disk requirements of about N⁴/2 for closed-shell と 3N⁴/4 for open-shell.
• EOM-CCSD initially sets its space requirements to its minimum needs. If this amount is more than MaxDisk, it obeys the latter at the expense of I/O と computation time.