Vqµ = − qµ / (4π ε0εr r2)
Say you had a negative charge, interacting with the positive end of a dipole then the charge would be -1.602 x 10-19 C and the dipole moment would always be a positive value. This means Vqµ would always be positive.
However a negative charge interacting with the positive end of a dipole is an attractive interaction so Vqµ should be negative. What am I missing here?