methane to nothing with NO bond shrinkage
MASS
DH 1.008                             DH IS DUMMY PROTON (HYDROGEN)
DC 12.01                             DT IS DUMMY CARBON

BOND
DH-DC 331.       1.09                   Note that "dummy" bond doesn't shrink

ANGLE
DH-DC-DH    35.        109.5

NONB
  DH       0.000      0.00
  DC       0.000      0.00