Interparticle friction coefficient in Hertz-Mindlin contact law

Hello,

If I want to simulate a simple shear with the Hertz-Mindlin contact law with an interparticle friction coefficient of 0.5, is it correct to just set the friction angle as 0.5 in the O.material [1] for each particle, or it has to be set in the Mindlinphys [2] for all particle interactions?
I think the friction angle used in O.material is the internal friction angle, which is not the interparticle friction angle, right?
I am a bit confused about this.

Thanks.

[1] https://yade-dem.org/doc/yade.wrapper.html?highlight=materials#yade.wrapper.FrictMat.frictionAngle
[2] https://yade-dem.org/doc/yade.wrapper.html?highlight=mindlinphys#yade.wrapper.Ip2_FrictMat_FrictMat_MindlinPhys.frictAngle

Chien-Cheng