1) I implemented the D flip flop circuit which I found on google and did the circuit connections as shown in the reference circuit in my literature survey.
2) I performed the electric rule check and there were no errors in the circuit.
3) Further on I generated the netlist of the circuit and edited the .cir file using notepad , I replaced mosfet_p with sky130_fd_pr__pfet_01v8 and mosfet_n with sky130_fd_pr__nfet_01v8 instruction to generate the waveform using SkyWater 130nm.
4) While running the circuit on ngspice I got an error "unable to find definition of model" inorder to rectify this error I had to rename the inputs sleep sleep_bar and clk with vsleep vsleep_bar and vclk , after renaming the inputs the circuit was simulated and output waveform was obtained 