Hard Convergence of SCF using OT algorithm within PERIODIC_EFIELD

[yonghao-zhu]

Hi, guys. In the MD running with periodic electric field, the SCF suddenly becomes hard to converge. The electric field sets to 0.001 a.u.. The figure is the .ener file. The last column is the time calculating corresponding ionic step. DIIS algorithm is used. Moreover, the bandgap of the system is 0.6 eV. In the smaller system, bewilderingly, calculations are easy to converge.