|ADAPTIVE||An adaptive grid is used for the integration. This is the default.|
|FIXED||A fixed grid is used for the integration.|
|MEDIUM||Medium grid accuracy is requested. This is the default.|
|COARSE||Coarse grid accuracy is requested.|
|FINE||Fine grid accuracy is requested.|
|REFERENCE||A (fixed) reference grid is requested.|
|TOL=Real||Adaptive grid tolerance.|
|RAD=Integer||Number of radial shells for adaptive grid.|
|SCF||The converged SCF density is used for the adaptive grid generation. This is the default.|
|GUESS||The start density is used for the adaptive grid generation.|
|DIRECT||The grid coordinates and weights are rebuilt in each SCF cycle. This is the default for parallel runs.|
Fixed grids are also available in deMon2k. They can be selected by the option FIXED in combination with the options COARSE, MEDIUM, and FINE. MEDIUM is the default for fixed grids. With the options COARSE, MEDIUM, and FINE, the pruned grids (50,194)p, (75,302)p and (99,590)p are selected. In this notation the first number refers to the radial shells and the second to the number of Lebedev grid points  on each of these shells. The "p" stands for pruned , which indicates that, for some radial shells, smaller Lebedev grids have been used. With the REFERENCE option, the fixed unpruned (200,1202) reference grid is specified. Due to its size, its application should be restricted to small systems.
The DIRECT option is used to avoid the I/O of the grid point coordinates and weights. With this option, the grid is built on the fly in each SCF step. This results in a small additional computational overhead. For serial runs, the I/O of the grid data is usually not significant. However, this behavior is architecture dependent. In parallel runs, the grid I/O becomes a bottleneck. Therefore, the DIRECT option is the default setting in such calculations.