make: Entering directory `/home/alvinche/lammps-21May08/src/Obj_usher'
g++ -g -O -L../STUBS angle_charmm.o angle_cosine.o angle_cosine_delta.o ...
/usr/bin/ld: cannot find -lmpi
Looks like you forgot to compile the stub MPI library in the STUBS directory. See this in http://lammps.sandia.gov/doc/Section_start.html#2_2:
"(4) If you just want LAMMPS to run on a single processor, you can use
the STUBS library in place of MPI, since you don't need an MPI library
installed on your system. See the Makefile.serial file for how to
specify the -I and -L switches. You will also need to build the STUBS
library for your platform before making LAMMPS itself. From the STUBS
dir, type "make" and it will hopefully create a libmpi.a suitable for
linking to LAMMPS. If the build fails, you will need to edit the
STUBS/Makefile for your platform"