[ESPResSo-users] mathematical description of the argument rinertia by using rigid arrangement of particles

[Holst, Lena]

Hello,

 

I have an question about the argument “rinertia”, that can be set by using rigid arrangement of particles. “rinertia” has the elements “x y z”.

Does means x: J_x = sum_i(m_i(x_i^2 + y_i^2))

                     Y: J_y = sum_i(m_i(x_i^2 + z_i^2))

                     Z: J_z = sum_i(m_i(x_i^2 + y_i^2))

Where i reaches from 1 to N (N is the number of virtual sites), m is the mass of one virtual site, and x,y,z the coordinates of the position of the virtual sites, if the point of origin is the position of the non-virtual site. J_x, J_y, J_z are the moments of inertia ordered to the coordinate axis.

 

If the assumption is correct, can I say the rigid object has the mass M = sum_i(m_i) + m? Where the non-virtual particle in the center of mass has the same mass m as the virtual sites.

 

Kind regards and thanks a lot,

Lena Holst

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