  The instability of nuclear matter due to particle-hole excitation modes has
been studied in the frame-work of several relativistic mean field (RMF) models.
It is found that both the longitudinal and the transversal modes depend
sensitively on the parameter sets used. The important impact of the vector and
vector-scalar nonlinear terms on the stability of both modes is demonstrated.
Our finding corroborates the result of previous studies, namely that certain
RMF models cannot be used in high density applications. However, we show that
for certain parameter sets of RMF models this shortcoming can be alleviated by
adding these nonlinear terms.
