Using Molden with GAUSSIAN

When using Molden with GAUSSIAN 94/98/03 the following keywords are required on the GAUSSIAN 94/98/03 inputfile:
```
    #P GFINPUT IOP(6/7=3)
```
#P switches on printing of SCF convergence, GFINPUT switches on printing of Basis Set info, and IOP(6/7=3) switches on printing of all MO's. GAUSSIAN 94/98 per default uses the redundant coordinates optimization procedure resulting in only cartesian coordinates being available on the output file. Molden will covert these into a z-matrix which in general will have lost the dummys and therefore symmetry at the z-matrix level. Use the gaussian keyword opt=z-matrix to get z-matrices on the output.
When using Molden with GAUSSIAN 92 and older versions, use:
```
    #P GFINPUT IOP(6/7=1)
```
Never use output of compound jobs (f.i. an optimisation followed by a frequency calculation, gaussian keywords opt freq ). You should split up the output of compound jobs into separate files, for Molden to work correctly.
Molden will warn you:
```
 WARNING: composite optimisation/frequency job
 The frequency job should be a separate file
 With First line:
  
  Entering Gaussian System
```
To split up the file, look for the string Normal termination of Gaussian , this is the end of the first run, now split the file up in two parts. (In the vi editor:
```
/Normal termination
:.,$w output2
:.,$d
:x
```
)
Be sure to add the following line to the second file:
```
 Entering Gaussian System
```
If you use the non-split up output, the geometrie optimisation structures will not be updated when youe use the next or movie buttons.
Molden does not support the use of Effective Core Potentials. Although the orbitals of such a calculation can be visualised and are valid.
Beware of using non-readible characters on the output (such as the date in russian), molden will think it is dealing with a binary format (mopac .gpt or msf).
The use of #T (Terse output) can give problems with molden.
For Gaussian98 and upwards the default is to print the Z-matrix and resultant coordinates ONLY for 50 atoms or less. To have Gaussian98 also print this information if the number of atoms is bigger than 50, add the following keywords:
```
    IOP(2/11=1)
```
When gaussian reads the basisset from cards (/gen option) be sure to have the correct contraction coefficients. Gaussian will renormalize after it has printed the basisset, causing molden to use the wrong contraction coefficients.
When doing MP2 calculations and you want molden to read the MP2 density add the gaussian keyword: pop=(naturalorbitals)
Check here how to setup Molden so that you can start gaussian jobs from the Molden interface.
Read here how to tell gaussian to print NLMO's from a NBO analysis (in addition to the extra keywords to print the basisset).
IRC gaussian calculations are now directly supported by Molden.
Molden (3.5 and upwards) supports Gaussian Cube files. Start molden without a file specified on the commandline. Go to the density mode, and click "cube file". You should not specify the cube file on the commandline.
You should use the molden keyword GAUCUB=filename instead of the molden keyword FILE=filename to specify a cube file in the keyword mode.