FeynAmpDenominatorExplicit[exp] changes each occurrence
of PropagatorDenominator[a,b] in exp into
1/(SPD[a,a]-b^2) and replaces
FeynAmpDenominator by Identity.
Overview, FeynAmpDenominator, PropagatorDenominator.
FAD[{q, m}, {q - p, 0}]
FeynAmpDenominatorExplicit[%]
% // FCE // StandardForm\frac{1}{\left(q^2-m^2\right).(q-p)^2}
\frac{1}{\left(q^2-m^2\right) \left(-2 (p\cdot q)+p^2+q^2\right)}
\frac{1}{\left(-m^2+\text{SPD}[q,q]\right) (\text{SPD}[p,p]-2 \;\text{SPD}[p,q]+\text{SPD}[q,q])}
Notice that you should never apply
FeynAmpDenominatorExplicit to loop integrals. Denominators
in a proper loop integral should be written as
FeynAmpDenominators. Otherwise, the given integral is
assumed to have no denominators and consequently set to zero as being
scaleless.
TID[FVD[q, mu] FAD[{q, m}, {q - p, 0}], q]\frac{\left(m^2+p^2\right) p^{\text{mu}}}{2 p^2 q^2.\left((q-p)^2-m^2\right)}-\frac{p^{\text{mu}}}{2 p^2 \left(q^2-m^2\right)}
TID[FeynAmpDenominatorExplicit[FVD[q, mu] FAD[{q, m}, {q - p, 0}]], q]0