[QE-users] vc-relax not converge and the energy cycles

[sha.liu]

Dear Sir,

I am running vc-relax using pw.x. But now, some structures are still not 
converged. The energy and enthalpy are cycling in some values. Please 
tell me why this happen? And how to solve it? Thank you~


      number of scf cycles    =  28
      number of bfgs steps    =  24

      enthalpy old            =    -264.9902566026 Ry
      enthalpy new            =    -264.9902565846 Ry

!    total energy              =    -264.99025637 Ry
      Harris-Foulkes estimate   =    -264.99025637 Ry
      estimated scf accuracy    <          1.2E-09 Ry


      number of scf cycles    =  29
      number of bfgs steps    =  24

      enthalpy old            =    -264.9902566026 Ry
      enthalpy new            =    -264.9902563710 Ry

!    total energy              =    -264.99025656 Ry
      Harris-Foulkes estimate   =    -264.99025657 Ry
      estimated scf accuracy    <          3.7E-09 Ry

      number of scf cycles    =  30
      number of bfgs steps    =  24

      enthalpy old            =    -264.9902566026 Ry
      enthalpy new            =    -264.9902565625 Ry

!    total energy              =    -264.99025639 Ry
      Harris-Foulkes estimate   =    -264.99025640 Ry
      estimated scf accuracy    <          7.5E-09 Ry

      number of scf cycles    =  31
      number of bfgs steps    =  24

      enthalpy old            =    -264.9902566026 Ry
      enthalpy new            =    -264.9902563914 Ry

!    total energy              =    -264.99025656 Ry
      Harris-Foulkes estimate   =    -264.99025656 Ry
      estimated scf accuracy    <          3.8E-09 Ry

      number of scf cycles    =  32
      number of bfgs steps    =  24

      enthalpy old            =    -264.9902566026 Ry
      enthalpy new            =    -264.9902565602 Ry

!    total energy              =    -264.99025640 Ry
      Harris-Foulkes estimate   =    -264.99025640 Ry
      estimated scf accuracy    <          2.1E-09 Ry

Regards,
Sha