MOLCAS manual:

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Subsections

8.35 `Mula`

The MULA calculates intensities of vibrational transitions between electronic states.

8.35.1 Dependencies

The MULA program may need one or more UNSYM files produced by the MCLR program, depending on input options.

8.35.2 Files

8.35.2.1 Input files

File	Contents
UNSYM	Output file from the `MCLR` program

8.35.2.2 Output files

File Contents
plot.intensity Contains data for plotting an artificial spectrum.

8.35.3 Input

The input for MULA begins after the program name:
&MULA

There are no compulsory keyword.

8.35.3.1 Keywords

Keyword Meaning
TITLe Followed by a single line, the title of the calculation.
FORCe A force field will be given as input (or read from file), defining two oscillators for which individual vibrational levels and transition data will be computed.
ATOMs Followed by one line for each individual atom in the molecule. On each line is the label of the atom, consisting of an element symbol followed by a number. After the label, separated by one or more blanks, one can optionally give a mass number; else, a standard mass taken from the file data/atomic.data. After these lines is one single line with the keyword "END of atoms".
INTErnal Specification of which internal coordinates that are to be used in the calculation. Each subsequent line has the form 'BOND a b' or 'ANGLE a b c' or or 'TORSION a b c d' or or 'OUTOFPL a b c d', for bond distances, valence angles, torsions (e.g. dihedral angles), and out-of-plane angles. Here, a...d stand for atom labels. After these lines follows one line with the keyword "END of internal".
MODEs Selection of modes to be used in the intensity calculation. This is followed by a list of numbers, enumerating the vibrational modes to use. The modes are numbered sequentially in order of vibrational frequency. After this list follows one line with the keyword "END of modes".
MXLEvels Followed by one line with the maximum number of excitations in each of the two states.
VARIational If this keyword is included, a variational calculation will be made, instead of using the default double harmonic approximation.
TRANsitions Indicates the excitations to be printed in the output. Followed by the word FIRST on one line, then a list of numbers which are the number of phonons – the excitation level – to be distributed among the modes, defining the vibrational states of the first potential function (force field). Then similarly, after a line with the word SECOND, a list of excitation levels for the second state.
ENERgies The electronic T₀ energies of the two states, each value is followed by either "eV" or "au".
GEOMetry Geometry input. Followed by keywords FILE, CARTESIAN, or INTERNAL. If FILE, the geometry input is taken from UNSYM1 and UNSYM2. If CARTESIAN or INTERNAL, two sections follow, one headed by a line with the word FIRST, the other with the word SECOND. For the CARTESIAN case, the following lines list the atoms and coordinates. On each line is an atom label, and the three coordinates (x,y,z). For the INTERNAL case, each line defines an internal coordinate in the same way as for keyword INTERNAL, and the value.
MXORder Maximum order of transition dipole expansion. Next line is 0, if the transition dipole is constant, 1 if it is a linear function, etc.
OSCStr If this keyword is included, the oscillator strength, instead of the intensity, of the transitions will calculated.
BROAdplot Gives the peaks in the spectrum plot an artificial halfwidth. The default lifetime is $130\cdot10^{-15}$ s but this can be changed with keyword LIFEtime followd by the value.
NANOmeters If this keyword is included, the plot file will be in nanometers. Default is in eV.
CM-1 If this keyword is included, the plot file will be in cm^-1. Default is in eV.
PLOT Enter the limits (in eV, cm^-1, or in nm) for the plot file.
VIBWrite If this keyword is included, the vibrational levels of the two states will be printed in the output.
VIBPlot Two files, plot.modes1 and plot.modes2, will be generated, with pictures of the normal vibrational modes of the two electronic states.
HUGElog This keyword will give a much more detailed output file.
SCALe Scales the Hessians, by multiplying with the scale factors following this keyword.
DIPOles Transition dipole data. If MXORDER=0 (see above), there follows a single line with x,y,z components of the transition dipole moment. If MXORDER=1 there are an additional line for each cartesian coordinate of each atom, with the derivative of the transition dipole moment w.r.t. that nuclear coordinate.
NONLinear Specifies non-linear variable substitutions to be used in the definition of potential surfaces.
POLYnomial Gives the different terms to be included in the fit of the polynomial to the energy data.
DATA Potential energy surface data.

8.35.3.2 Input example

&MULA Title Water molecule Atoms O1 H2 H3 End Atoms Internal Coordinates Bond O1 H2 Bond O1 H3 Angle H3 O1 H2 End Internal Coordinates MxLevels 0 3 Energies First 0.0 eV Second 3.78 eV Geometry Cartesian First O1 0.0000000000 0.0000000000 -0.5000000000 H2 1.6000000000 0.0000000000 1.1000000000 H3 -1.6000000000 0.0000000000 1.1000000000 End Second O1 0.0000000000 0.0000000000 -0.4500000000 H2 1.7000000000 0.0000000000 1.0000000000 H3 -1.7000000000 0.0000000000 1.0000000000 End ForceField First state Internal 0.55 0.07 0.01 0.07 0.55 0.01 0.01 0.01 0.35 Second state Internal 0.50 0.03 0.01 0.03 0.50 0.01 0.01 0.01 0.25 DIPOles 0.20 0.20 1.20 BroadPlot LifeTime 10.0E-15 NANO PlotWindow 260 305 End of input

&MULA TITLe Benzene ATOMs C1 C2 C3 C4 C5 C6 H1 H2 H3 H4 H5 H6 End of Atoms GEOMetry file INTERNAL COORDINATES Bond C1 C3 Bond C3 C5 Bond C5 C2 Bond C2 C6 Bond C6 C4 Bond C1 H1 Bond C2 H2 Bond C3 H3 Bond C4 H4 Bond C5 H5 Bond C6 H6 Angle C1 C3 C5 Angle C3 C5 C2 Angle C5 C2 C6 Angle C2 C6 C4 Angle H1 C1 C4 Angle H2 C2 C5 Angle H3 C3 C1 Angle H4 C4 C6 Angle H5 C5 C3 Angle H6 C6 C2 Torsion C1 C3 C5 C2 Torsion C3 C5 C2 C6 Torsion C5 C2 C6 C4 Torsion H1 C1 C4 C6 Torsion H2 C2 C5 C3 Torsion H3 C3 C1 C4 Torsion H4 C4 C6 C2 Torsion H5 C5 C3 C1 Torsion H6 C6 C2 C5 END INTERNAL COORDINATES VIBPLOT cyclic 4 1 ENERGIES First 0.0 eV Second 4.51 eV MODES 14 30 5 6 26 27 22 23 16 17 1 2 9 10 END MXLE - MAXIMUM LEVEL of excitation (ground state - excited state) 2 2 MXOR - MAXIMUM ORDER in transition dipole. 1 OscStr Transitions First 0 Second 0 1 2 FORCEFIELD First file Second file DIPOLES file