2\delta_{\mu \nu}$. Our aim is to solve the DSE for the renormalised quark propagator $S(p,\mu)$, which we write in the form $$\begin{aligned}
S(p,\mu) & = & \frac{1}{i\gamma\cdot p A(p^2,\mu^2) + B(p^2,\mu^2)} 
                                       \nonumber \\
    & = & \frac{1}{Z_2(\mu^2,\Lambda^2)[i\gamma\cdot p + m_0(\Lambda)] 
               + \Sigma^{'}(p,\Lambda)} .   \label{genprop}\end{aligned}$$ The unrenormalised self energy is written $$\Sigma'(p,\Lambda) = i\gamma\cdot p \left[A'(p^2,\Lambda^2) - 1\right]
       + B'(p^2,\Lambda^2).  \label{Sigpr}$$

If the renormalisation scale is set such that $$\left.S(p)\right|_{p^2 = \mu^2}=\frac{1}{i\gamma\cdot p + m_R(\mu^2)},
                            \label{mufix}$$ it follows from Eqs. (\[genprop\]) and (\[Sigpr\]) that renormalised and bare quantities are related by $$Z_2(\mu^2,\Lambda^2) = 2 - A'(\mu^2,\Lambda^2),  \label{Zfix}$$ $$A(p^2,\mu^2) = 1 + A'(p^2,\Lambda^2) - A'(\mu^2,\Lambda^2), \label{AApr}$$ $$B(p^2,\mu^2) = m_R(\mu^2) + B'(p^2,\Lambda^2) - B'(\mu^2,\Lambda^2). 
                     \label{BBpr}$$

The set of equations (\[DSEqn\]) and (\[Zfix\]) to (\[BBpr\]) together with the ‘abelian approximation’ $Z_1 = Z_2$ can be solved numerically for the propagator functions $A$ and $B$ once the renormalised quark-gluon vertex function $\Gamma_\mu$, the renormalised gluon propagator $D_{\mu \nu}$, the renormalisation point $\left(\mu,m_R(\mu)\right)$ and cutoff $\Lambda$ are specified. The precise forms of the quark-gluon vertex and gluon propagator are unknown and must be modelled by appropriate Ansätze. We next summarise the Ansätze employed in this paper.

Quark-gluon vertex
------------------

The most general form of the quark-gluon 