How to accelerate the convergence for optimization of MECI

[panwangzhou]

Dear all,

Recently I used the XMS-CASPT2 to optimize the MECI between S0 and S1 of a molecule with BAGEL, I have sucessfully located the MECI at SA2-CASSCF level and used it as the start geometry for the XMS-CASPT2 calculation. After 77 cycles I found that there is no good convergence trend, then I kill the job, change the maxstep to 0.01, reduce the convergen threshold, and resubmit the job. However, the convergence trend did not change significantly. So I want to know which parameters are helpful for MECI optimization? The optimization method, the method of updating hessian, or the method for calcualting NACME, etc.

Part of input file: { "title" : "optimize", "opttype" : "meci", "target" : 0, "target2" : 1, "maxziter" : 200, "maxstep" : 0.01, "maxgrad" : 0.003, "maxdisp" : 0.012, "maxchange" : 0.00003, "molden" : "true", "method" : [ { "title" : "caspt2", "smith" : { "method" : "caspt2", "ms" : "true", "xms" : "true", "sssr" : "true", "shift" : 0.2, "frozen" : true, "maxiter" : 100 }, "charge" : 0, "nstate" : 2, "nact" : 8, "nclosed" : 86, "natocc" : "true", "maxiter" : 200, "restart_cas" : "true" } ] },

The last of the outpuf file: Conical intersection optimization started iter energy gap energy grad rms time

  1      -1373.17543386          0.00003656          0.00351362     2903.75
  2      -1373.17520381          0.00120217          0.00361351     3029.68
  3      -1373.17429411          0.00101771          0.00342756     2951.25
  4      -1373.17478220          0.00049427          0.00300190     3202.36
  5      -1373.17560701          0.00061631          0.00293842     3156.61
  6      -1373.17539582          0.00022999          0.00534487     3344.72