Resonance and intermediate-coupling effects in electron scattering with highly charged ions. III. ${\mathrm{Ca}}^{18+}$

Effective collision strengths are presented for all 78 inelastic transitions, including the fine structure, involving the states $1s^2\left({}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}\right)$, $1s2s({}_{}{}^3{}_{}{}^{}S_1^{}{}_{}{}^{},{}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{})$, $1s2p({}_{}{}^3{}_{}{}^{}P_{0,1,2}^{}{}_{}{}^{},{}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{})$, $1s3s({}_{}{}^3{}_{}{}^{}S_1^{}{}_{}{}^{},{}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{})$, and $1s3p({}_{}{}^3{}_{}{}^{}P_{0,1,2}^{}{}_{}{}^{},{}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{})$ in ${\mathrm{Ca}}^{18+}$. Resonance effects due to autoionization and dielectronic recombination are considered as in earlier papers. Departure from $\mathrm{LS}$ coupling, due to relativistic effects, is included with use of the Breit-Pauli approximation. A nine-state distorted-wave approximation is employed for partial waves $l,l^{\prime }\le 15$; the contribution from $l>\mathrm{}15\mathrm{}$ to optically allowed transitions is treated by the Coulomb-Bethe method. Dipole oscillator strengths for 28 allowed transitions are also calculated. Resonance and relativistic effects are shown to be important for a number of transitions.