I had run a Raman simulation but failed! The 'Ce38Gd2O79p 245_Efield.castep' shows:

Perturbation    2 (of  357): O     2 X at q=( 0.000, 0.000, 0.000):    486.51s

Writing model to Ce38Gd2O79p_245_Efield.check

Perturbation    3 (of  357): O     3 X at q=( 0.000, 0.000, 0.000):   1684.28s

Perturbation    4 (of  357): O     4 X at q=( 0.000, 0.000, 0.000):   2174.71s

Writing model to Ce38Gd2O79p_245_Efield.check

Perturbation    5 (of  357): O     5 X at q=( 0.000, 0.000, 0.000):   2678.76s

Writing model to Ce38Gd2O79p_245_Efield.check

Perturbation    6 (of  357): O     6 X at q=( 0.000, 0.000, 0.000):   3856.52s

Secondd_minimise_phonon_E2: Can not converge to requested precision in 100 iterations

        Best convergence achievable is 0.230769E-03eV/A**2  

        Consider increasing PHONON_MAX_CYCLES or convergence tolerance PHONON_ENERGY_TOL

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Writing checkpoint file

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Writing model to Ce38Gd2O79p_245_Efield.check

Error in PHONON_LINEAR_RESPONSE.  DFPT convergence failed - aborting

Current trace stack:

phonon_linear_response

phonon_dynamical_matrix

phonon_calculate_std_kpoints

phonon_calculate

castep

Last known process information:

===============================

So I check the Phonons in the properties tab,

and change the PHONON_ENERGY_TOL into 2.5e-4, which is higher than 0.230769E-03eV/A**2.

but when I re-run with the Phnons properties, it failed again and the 'Ce38Gd2O79p 245_PhonDOS.castep' shows:

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?                                                                              ?

?     *ERROR* in PHONON calculation:  Prerequisite GEOMETRY OPTIMISATION       ?

?     has not been performed or is not converged to sufficient accuracy.       ?

?                                                                              ?

?        Maximum force |F|max     = 0.3546     eV/A                            ?

?        Parameter GEOM_FORCE_TOL = 0.1000     eV/A                            ?

?                                                                              ?

?   This could be because of any of the following                              ?

?     (a) No geometry optimisation was performed                               ?

?     (b) A geometry optimisation failed to converge                           ?

?     (c) An error was made copying the optimised geometry to this .cell file  ?

?     (d) Cutoff, k-point sampling or other convergence parameter differ       ?

?         from the geometry optimisation run to this one.                      ?

?   Please check your input parameters and if necessary run or re-run a        ?

?   geometry optimisation calculation.                                         ?

?                                                                              ?

?   Alternatively increase value of GEOM_FORCE_TOL to 0.3546     or greater    ?

?   to allow this run to proceed at risk of inaccurate phonon frequencies.     ?

?                                                                              ?

?   Typically a force tolerance convergence of 0.025 eV/A is necessary to      ?

?   obtain well converged phonon frequencies althout a smaller value can be    ?

?   required in the presence of weak forces, e.g. in molecular crystals        ?

?                                                                              ?

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ERROR: Phonon run aborted because of unoptimised geometry. See Ce38Gd2O79p_245_PhonDOS.castep for more details

Current trace stack:

phonon_check_geometry

phonon_calculate

castep

Last known process information:

===============================

Could anyone tell what I can do to run the raman succefully?