vector.
 Such an approach (known as the local lattice approach) is based on the
assumption that the
deformations are small and smooth functions of position and time and
possesses
all shortcomings of any linearized theory. In addition,
the kinetic equation
becomes incompatible with the requirement of the periodicity.
 To avoid
any misunderstandings, note that Eqs.(1) and (2)
are written in the co-moving frame.



    The second problem is related to the fact that the crystal lattice
plays the role of a privileged coordinate frame and no Galilean
transformations for quasiparticle characteristics exist.
 The lack of transformation laws for such quantities as energy,
Hamiltonian and quasimomentum means, in fact, that there is no consistent
quasiparticle mechanics. The most fundamental
quantity, the dispersion law, is known in a co-moving frame attached to
the lattice and this frame is even not inertial at time-varying
deformations. On the
other hand, all fundamental physical equations, such as conservation laws,
variational principles, kinetic eqs. etc. take place in the laboratory
frame ($L$-system). However  the concept of dispersion law does not exist in
$L$-system. Hence, in principle, even if  the mechanics equations for
a quasiparticle were known in $C$-system, they remain unknown in $L$-system.
\par
    These problems are 