Keyword DAVIDSON

This keyword controls the DAVIDSON diagonalization during a TDDFT calculation. This keyword has no effect if the keyword EXCITATION is not active.
Options:

	BAS=$<$Integer$>$		The maximum size of the basis to be used in the iterative process, i.e., the size of the matrix to be diagonalized. The default value is 30.
	EIG=$<$Integer$>$		The number of the lowest excited states to be used in the iterative process. The default value is 10.
	MAX=$<$Integer$>$		The maximum number of iterations to be used in the iterative process. The default value is 500.
	TOL=$<$Real$>$		The convergence criterion. The default value is $10^{-5}$.

Description:
In deMon2k the block Davidson algorithm [286] is used for finding the lowest eigenvalues and eigenvectors of the large TDDFT matrix.