GetForce returns NaN
If a geometry has two atoms which x and y coordinates are exactly same, GetForce returns a vector that contains NaN.
This bug is found in r1105
I found a "theoretical" bug which causes this NaN in r1105.
The variable "double r" in the Cndo2::CalcRotatingMatrix1stDerivatives is 0 when x=y=0, which leads to 0-divide.
The variable "double r" in the Cndo2::CalcRotatingMatrix2ndDerivatives causes same error.
To fix these bugs, re-fomulation of the 1st and 2nd derivatives of rotating matrix is needed
Fixed at r1305. When x=y=0, the rotating is not needed.