General

To search a minimum energy path (MEP) in geometrical phase space connecting two stable structures, a nudged elastic band (NEB) method based on Ref. [134] is supported in OpenMX Ver. 3.9. The detail of the implementation is summarized as follows:

• Calculation of tangents based on Eqs. (8)-(11) in Ref. [134]

• Calculation of perpendicular forces based on Eq. (4) in Ref. [134]

• Calculation of parallel forces based on Eq. (12) in Ref. [134]

• Optimization method based on a hybrid DIIS+BFGS optimizer

In order to minimize user's efforts in using it, the functionality of NEB has been realized as one of geometry optimizers with the following features:

• Easy to use

• Hybrid MPI/OpenMP parallelization

• Initial path by the straight line or user's definition

• Only three routines added