PROGRAM CIS-T (version 2.3)
                        
                             I, Mayer
                          Budapest, 2006/2014

This program performs post-processing of the CIS or TDHF, TDDFT wave 
functions obtained in a Gaussian (G94 ... G09) run, by using the 
"singular value decomposition" method (I. Mayer, Chem. Phys. Letters, 437, 
284, 2007; for systems with two chromophores see also ibid. 443, 420, 
2007). That means computing optimized occupied and virtual orbitals by the 
use of which the CIS (TDHF, TDDFT) wave function can be presented as a sum 
of no more than "n" excitations, where "n" is the smaller of the number of 
the occupied and virtual orbitals. Only the Gaussian output file is 
necessary, provided that the CI coefficients are printed with a small 
enough threshold: the required format is "IOp(9/40=6) Pop=full". E.g. the 
Gaussian input cards may be:

Version 2.3 incorporates minor changes that were required for the use with 
Gaussian-09 as well as for a larger number of orbitals. (The minor changes 
permitting compilation with both "g77" and "gfortran" have also been 
introduced.)


---------------------------------------
%Mem=1000MB
# HF/6-31G** SCFCYC=200 SCF=Tight  GFInput Pop=full
  CIS(Conver=6,Nstates=10) IOp(9/40=6)

Pentanone

 0 1
 6          -0.035291   -1.232463    0.123575
 6           1.371558   -0.735508   -0.227800
 6           1.371567    0.735504    0.227783
 6          -0.035291    1.232466   -0.123552
 6          -0.921644    0.000000    0.000003
 8          -2.110417    0.000000   -0.000012
 1          -0.406895   -2.038253   -0.497524
 1          -0.086100   -1.567976    1.157511
 1           1.525061   -0.785971   -1.302941
 1           2.156891   -1.318444    0.238735
 1           1.525101    0.785966    1.302921
 1           2.156889    1.318436   -0.238773
 1          -0.086122    1.568013   -1.157475
 1          -0.406882    2.038237    0.497580

---------------------------------------

Use of the program:

CIS-T < input.file > output.file

Required input:
--------------

Two or three cards:

1. Name of the Gaussian output file to be processed
2. Istat: ordinal number of the excited state to be processed (free
   format)

Example of input for the third CIS state of the pentanone molecule:
 
---------------------------------------
pentanone-CIS.log
  3
--------------------------------------

Special manipulation:

3. If a 3d card is also present and contains the number 1 (free format),
then special manipulations will be performed: instead of the first two
occupied orbitals their normalized sum and difference is computed, and
similarly for the first two virtual orbitals. They may correspond to
two coupled local excitations.  (Where the orbitals are printed, the first 
two lambda values are also replaced by the square root of their mean square.)

Example: input for the first exited state of cyclohexandiole molecule with 
recovering the local excitations as sums of differences (I. Mayer, CPL, 443, 
420, 2007):

---------------------------------------
ciklohexo2.log
 1
 1
---------------------------------------


Output
______

Two output files:

1, The file "output.file" as given at the execution.

The most important quantities:

a) The norm of the CIS wave function (for the given spin) as
computed from the CI coefficients. It should be very close to 0.5 for
CIS, not for TDHF or TDDFT. Then a renormalization to 0.5 is done.

b) The values of the lambda parameters as obtained on the SVD procedure;

c) The relative weights of the contribution to the given CIS state coming
from the excitation from the i-th transformed occupied orbital to the i-th
transformed virtual one. This weight is given in percents by 
200*(lambda_i)^2 ;

d) Transformation matrices U and V obtained in the SVD procedure;

e) The first 5 transformed occupied and transformed virtual orbitals
with the respective lambda values.


2. A file named CIS is generated which is similar to the Gaussian output
file which has been processed, but the first 5 transformed occupied and 5 
transformed are inserted as the first 10 molecular orbitals. (The
canonical MO-s are also present but shifted and somewhat spoiled.) 

This file may be used with the MOLDEN program to study the form of
the transformed occupied and virtual orbitals. (For studying the canonical
ones use the original Gaussian output!)

A temporary file Tmp is also generated. It is overwritten in the 
next calculation - as is file CIS, too, if has been not renamed.

The FORTRAN program is hopefully sufficiently standard to be run on
every system. Should be the number of occupied or virtual orbitals together
exceed 4000, the parameter "Large" should be increased accordingly
(in five places). 

The present version is applicable for the closed-shell case only.

Send remarks and questions to the address:
 
                      mayer@chemres.hu