\begin{table}%t1
%\centering
\par
\caption {\label{pf}Partition functions for \ion{Pr}{ii} and \ion{Pr}{iii}.} 
%
 %\tabcolsep1.2mm
\begin{tabular}{cccc}
\hline\hline\noalign{\smallskip}
%\cline{2-4}
 Temperature& \multicolumn{2}{c} {\ion{Pr}{ii}} & \ion{Pr}{iii}    \\
\cline{2-3}
   (K)     & Ginibre (1989) & this study & this study \\  
\hline
 3000 &~~55 &~~58&~22  \\
 4000 &~~91 &~101&~28  \\
 5000 &~138 &~166&~34  \\
 6000 &~192 &~251&~43  \\
 7000 &~252 &~356&~54  \\
 8000 &~315 &~478&~66  \\
 9000 &~380 &~617&~81  \\
10~000 &~446 &~770&~97  \\
11~000 &~511 &~937&114  \\
12~000 &~576 &1117&132  \\
13~000 &~639 &1309&151  \\
14~000 &~701 &1514&170  \\
15~000 &~762 &1732&190  \\
16~000 &~820 &1962&211  \\
17~000 &~878 &2205&231  \\
18~000 &~933 &2460&252  \\
19~000 &~986 &2727&273  \\
20~000 &1038 &3007&293  \\
\hline
\end{tabular} 
\end{table}