ps4 p2 done.
ps4 done.

modified:   ../../env/.aspell.en.prepl
modified:   ../../env/.aspell.en.pws
modified:   condensedMatterProblemSet4Problem1.tex
modified:   condensedMatterProblemSet4Problem2.tex
modified:   ../phy487/mathematica/qmSolidsPs4P2cAnimation.nb