fix thermal/conductivity command deal with molecular is done by atom exchange ??

Hi lammps users Recently,I tried this command fix thermal/conductivity to deal with the flexible molecules(zhang call atomic exchange), Zhang paper for a discussion and results of this idea, he said atomic exchange and molecular exchange( swap the molecular center-of-mass velocities) have less different. but my data Tc of water flexible SPC/E computed by atomic exchange is about 0.60 W/(mK) ,From the paper (Characteristics of thermal conductivity in classical water models),the Tc of water rigid SPC/E computed by molecular exchange is about 0.8~0.9W/(mK), so I don’t know why is so much different. This is in contrast with Zhang’s views.
I also find that the temperature gradient is somewhat tortuous(atomic exchange). Zhang also don’t given us the diagram of gradient gradient in his paper(atomic exchange).So I don’t know if I am wrong. But I think my program is certainly right.
Looking forward your reply!
Thanks
Jack zhuang

Hi lammps users
                     Recently,I tried this command fix
thermal/conductivity to deal with the flexible molecules(zhang call atomic
exchange), Zhang paper for a discussion and results of this idea, he said
atomic exchange and molecular exchange( swap the molecular center-of-mass
velocities) have less different. but my data Tc of water flexible SPC/E
computed by atomic exchange is about 0.60 W/(mK) ,From the paper
(Characteristics of thermal conductivity in classical water models),the Tc
of water rigid SPC/E computed by molecular exchange is about 0.8~0.9W/(mK),
so I don't know why is so much different. This is in contrast with Zhang's
views.

why should it *not* be different? you are comparing a rigid and a flexible
model, i would expect them to have different thermal conductivity.