We derive the 〈ξ| representation of the inverse of two particles' relative position which turns out to be an integration operation on the representation and is related to two particles' masses. The representation is useful in conveniently solving energy level formula for some dynamic systems.
We give the explicit form of the common eigenstate \ensuremath{\Vert}\ensuremath{\xi}〉 of the center-of-mass coordinate ${\mathrm{\ensuremath{\mu}}}_{1}$Q1+${\mathrm{\ensuremath{\mu}}}_{2}$Q2 and the mass-weighted relative momentum ${\mathrm{\ensuremath{\mu}}}_{2}$P1-${\mathrm{\ensuremath{\mu}}}_{1}$P2 of two particles, which is more complicated than the common eigenstate of the other pair of commutative operators Q2-Q1 and P1+P2. The orthonormal and completeness relation of \ensuremath{\Vert}\ensuremath{\xi}〉 are investigated easily by virtue of the technique of integration within an ordered product of operators. The normally ordered squeezing operator for ${\mathrm{\ensuremath{\mu}}}_{1}$Q1+${\mathrm{\ensuremath{\mu}}}_{2}$Q2 and ${\mathrm{\ensuremath{\mu}}}_{2}$P1-${\mathrm{\ensuremath{\mu}}}_{1}$P2 is also derived by using the \ensuremath{\Vert}\ensuremath{\xi}〉 representation.
We use the common eigenvectors \ensuremath{\Vert}\ensuremath{\zeta}〉 of two particles' center-of-mass position Xc=${\mathrm{\ensuremath{\mu}}}_{1}$X1+${\mathrm{\ensuremath{\mu}}}_{2}$X2 and mass-weighted relative momentum Pr=${\mathrm{\ensuremath{\mu}}}_{2}$P1-${\mathrm{\ensuremath{\mu}}}_{1}$P2, as well as the eigenvectors \ensuremath{\Vert}\ensuremath{\eta}〉 of the other pair commutative operators X=X1-X2 and P=P1+P2 to solve the dynamics of two coupled oscillators. The coupling involves both interbond potential and kinetic coupling. This approach seems to be simple, convenient, and natural. \textcopyright{} 1996 The American Physical Society.
We solve the inverse problem corresponding to the fundamental problem of the classical dynamics of a material particle through a matrix treatment: assuming knowing the mass and the position (the trajectory, in relation to an inertial reference) of a particle at all times, we impose that this corresponds to the eigenvector of a “position matrix". Subsequent development leads to a “force matrix", which has the resultant force on the particle as its eigenvector. We identified some limitations of this matrix treatment.