A highly accurate finite element method (FEM) [20] is available for all electron
calculations within LDA by Vosko, Wilk, and Nusair [2] and
the Hartree-Fock scheme. In the calculations, spherical charge distribution
and sherical potential are assumed for the Schrödinger equation.
The FEM calculation is not supported for the Dirac equation.
The following keywords are especially relevant for the FEM calculation:

**calc.type**

ALLFEM (FEMLDA) and FEMHF are available for the all electron LDA and HF calculations
using the finite element method (FEM) [11], respectively.
Note that due to a technical reason during development, two specifications,
ALLFEM and FEMLDA are equivalent to each other.

**grid.xmax**

In the FEM calculation, the grid is generated at regular intervals on a coordinate ,
where the relation between the radial coordinate and is given by .
The keyword, grid.xmax, specifies the upper bound of in this case. Note that
the definition of is different from the conventional calculations in ADPACK.
The lower bound of is always set to zero.

The roles of the other keywords are same as in the conventional calculations. Also, the database for all electron calculation performed by the FEM scheme can be found at http://www.openmx-square.org/miscellaneous.html. The database provides calculation results and input files used for the calculations. In the database, it is estimated based on the virial theorem [21] that the absolute error in the total energy is less than nano-Hartree and micro-Hartree for the LDA and HF calculations of all elements in the periodic table, respectively.