The optimized structure of my compound is generated in .log format but for the .chk format it shows the error as mentioned in question. With the .log format of optimized file I submitted the next job for analyzing HOMO and LUMO and received both .log , .chk file . But when I am opening .chk file it shows error like mentioned in question . Even I tried to generate .chk file separately then also the same error repeats. What should I do to get Molecular orbital diagram ?