6. Calculation of correlation functions

6.1. correlation

• Calculating correlation functions for a structure.

• Crystal lattice is determined by UPOSCAR and UPOTCAR files.

• Clusters for calculating correlations functions are specified by position.out.

• Available only for binary systems.

• Available for multi-thread calculations using OPENMP.

Input files

• CE.in

• UPOSCAR

• UPOTCAR

• POSCAR

• POTCAR

• position.out

Output files

• correlation.out

• of.out

6.2. CE.in

Example

Calculating correlation functions for a structure with the lattice constructed by the 2x1x1 expansion of UPOSCAR. Spin values are set to 1 and -1 for Mg and Zn, respectively.

ISUB = 1
NUCELLPOSCAR = 2 1 1
NAMEPOT = Mg Zn
SPIN = 1 -1

6.2.1. ISUB tag

Sublattice indexes for performing the CE. The CE is performed on ISUBth lattice sites of UPOSCAR (line 6).

• Default : 1

• Example : ISUB = 1 3

6.2.2. NUCELLPOSCAR tag

Number of unit cells included in POSCAR.

• Default : none

• Example : NUCELLPOSCAR = 2 1 1

6.2.3. NAMEPOT tag, SPIN tag

Atom names and spin values for the atom names. Do not set spin values for atoms which are not used for the CE.

• Default : none

• Example : NAMEPOT = Mg Zn

• Example : SPIN = 1 -1

In the above example, spin values for Mg and Zn are 1 and -1, respectively.

6.2.4. SYMPREC tag

Numerical precision for searching for symmetry operations (unit: fractional coordinates).

• Default : 1e-5

• Example : SYMPREC = 1e-5