              The [2][3] element of the standard anisotropic atomic\
               displacement matrix U, which appears in the structure factor\
               term as:\
\
               T = exp{-2 pi^2^ sum~i~[sum~j~(U~ij~ h~i~ h~j~ a*~i~ a*~j~)]}\
\
               h  = the Miller indices\
               a* = the reciprocal space cell lengths\
\
               These matrix elements may appear with atomic coordinates\
               in the ATOM_SITE category, or they may appear in the separate\
               ATOM_SITE_ANISOTROP category, but they may not appear in both\
               places. Similarly, anisotropic displacements may appear as\
               either B's or U's, but not as both.\
\
               The unique elements of the real symmetric matrix are\
               entered by row.