If anyone can answer the question that how to solve this error G0127 : File not open for write
This error is returned by the GAUSS function writer. To write to a file it must have been opened with either the GAUSS function create or open.
Most likely the open function returned a -1 which indicates an invalid file handle. This could be because you do not have permission to write to the file, or because the file does not exist--maybe because it is located in another directory.
If this is not enough to solve your problem, please post some more details and we will get it solved for you.