LO-TO splitting is a long-range effect, as such it only occurs in the vicinity of Gamma. You can try to make a copy of the force constant file, where you remove the effective charges, i.e. you remove these lines: T 2.2192318 0.0000000 0.0000000 0.0000000 2.2192318 0.0000000 0.0000000 0.0000000 3.5742157 1 -0.5300825 0.0000000 0.0000000 0.0000000 -0.5300825 0.0000000 0.0000000 0.0000000 -2.0015990 2 -0.5300825 0.0000000 0.0000000 0.0000000 -0.5300825 0.0000000 0.0000000 0.0000000 -2.0015990 3 1.0610398 0.0000000 0.0000000 0.0000000 1.0610398 0.0000000 0.0000000 0.0000000 4.0034960
and do the dispersion with matdyn again. You can then compare the two dispersion to see where the long range LO-TO splitting kicks in. > > Also, I want to know the details (or please refer any source or > tutorial) and difference of *"fleig"* and *"fldyn". *Surprisingly I was > not able to find any frequencies in fidyn out put file. My out put is as > follows -- Dr. Lorenzo Paulatto IdR @ IMPMC -- CNRS & Université Paris 6 phone: +33 (0)1 44275 084 / skype: paulatz www: http://www-int.impmc.upmc.fr/~paulatto/ mail: 23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05 _______________________________________________ Pw_forum mailing list Pw_forum@pwscf.org http://pwscf.org/mailman/listinfo/pw_forum