Dear Daniele,

Many thanks for your kind and helpful reply.

Cheers, Mohammad.

Mr. Taghartapeh,

Please find as attachment an input (opt/freq in DMF) using your output data (simulation-1-dmf.gjf).

You should pay attention to "solvent=generic" at:

http://www.gaussian.com/g_tech/g_ur/k_scrf.htm

The current solvent parameters (end of the molecule specification section) as shown in input file (eps=37.2, rsolv=2.647 and epsinf=2.0) are taken from reference J. Solid State Electrochem. 17 (2013) 3027.

To these parameters you can add, other, explicitly important ones, which to be taken into account for, too (output below):

-Molar volume [cm**3/mol];

-Thermal expansion coefficient [K**-1];

- Absolute temperature [K] (by default T = 298.15);

- Numeral density [Ang**-3];

- Hydrogen bond acidity;

- Hydrogen bond basicity;

- Surface tension at interface [(cal/mol)*Ang**-2];

- Carbon aromaticity;

- Electronegative halogenicity.

If you take into consideration specific solute-solvent interactions, via a mixed-solvation approach, for example, these parameters you should find and add to the parameters in "molecule specification section" as already shown. Because of, studying these interactions, it is important to account for accepting/donation ability of the solvent. Nevertheless that, these properties are of importance using polar protic solvents like CH3OH, rather than DMF.

Towards your structure, you have started, most probably, from a quinoide like structure (attachment). For such as dyes, however, there is an equilibrium between quinoide/aromatic bipolar forms of isolate dyes. In addition to set possible so-called aggregates (pi-stacking dye interactions of dimers-trimers). In this context, I am attaching you inputs of bipolar and quinoide dye forms, which you could optimize first in gas-phase, and then in DMF using already commented input details (Azo-bipolar.gjf, Azo-quinoide.gjf). They are with different starting electronic structures. If you have started from quinoide form, then you do not need Azo-quinoide.gjf input. If you study properties of such dyes, both forms should be compared, because of there are perturbations of values depending on the initial state. Furthermore, these perturbations are observed even experimentally, depending on the properties of the environment.

Please find below as well as an example of computed H2O (opt, freq) in GP and DMF, using the shown parameters of DMF (hf/6-31G(d) level):

GP H2O:

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

! Optimized Parameters !

! (Angstroms and Degrees) !

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

! Name Definition Value Derivative Info. !

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

! R1 R(1,2) 0.9475 -DE/DX = -0.0002 !

! R2 R(1,3) 0.9475 -DE/DX = -0.0002 !

! A1 A(2,1,3) 105.5346 -DE/DX = -0.0001 !

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

GradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGrad

A1 A1 B2

Frequencies -- 1826.5129 4068.3199 4186.7713

Red. masses -- 1.0823 1.0455 1.0829

Frc consts -- 2.1274 10.1954 11.1838

IR Inten -- 107.3054 18.1918 58.2041

Raman Activ -- 5.7251 75.6120 39.0886

Depolar (P) -- 0.5301 0.1831 0.7500

Depolar (U) -- 0.6929 0.3095 0.8571

H2O in DMF:

Using the following non-standard input for PCM:

dis rep cav nelpardump=relevant stoichiometry=C3H7N1O1

eps=37.2 rsolv=2.5 epsinf=2.0

--- end of non-standard input.

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

Polarizable Continuum Model (PCM)

=================================

Model : PCM.

Atomic radii : UFF (Universal Force Field).

Polarization charges : Total charges.

Charge compensation : None.

Solution method : Matrix inversion.

Cavity type : Scaled VdW (van der Waals Surface) (Alpha=1.100).

Cavity algorithm : GePol (No added spheres)

Default sphere list used, NSphG= 3.

Lebedev-Laikov grids with approx. 5.0 points / Ang**2.

Smoothing algorithm: Karplus/York (Gamma=1.0000).

Polarization charges: spherical gaussians, with

point-specific exponents (IZeta= 3).

Self-potential: point-specific (ISelfS= 7).

Self-field : sphere-specific E.n sum rule (ISelfD= 2).

1st derivatives : Analytical E(r).r(x)/FMM algorithm (CHGder, D1EAlg=3).

Cavity 1st derivative terms included.

Solvent : Generic,

Eps = 37.200000

Eps(infinity) = 2.000000

RSolv = 2.500000 Ang.

Molar volume = 0.000000 cm**3/mol

Thermal expansion coefficient = 0.000000 K**-1

Absolute temperature = 298.150000 K

Numeral density = 0.000000 Ang**-3

Hydrogen bond acidity = 0.000000

Hydrogen bond basicity = 0.000000

Surface tension at interface = 0.000000 (cal/mol)*Ang**-2

Carbon aromaticity = 0.000000

Electronegative halogenicity = 0.000000

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

Spheres list:

ISph on Nord Re0 Alpha Xe Ye Ze

1 O 1 1.750 1.100 0.000000 0.000000 0.126981

2 H 2 1.443 1.100 0.000000 0.756789 -0.507924

3 H 3 1.443 1.100 0.000000 -0.756789 -0.507924

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

GePol: Number of generator spheres = 3

GePol: Total number of spheres = 3

GePol: Number of exposed spheres = 3 (100.00%)

GePol: Number of points = 384

GePol: Average weight of points = 0.15

GePol: Minimum weight of points = 0.12D-03

GePol: Maximum weight of points = 0.20212

GePol: Number of points with low weight = 9

GePol: Fraction of low-weight points (

Dear Professor  Ivanova,

Many thanks for your kind reply. 

Cheers,Mohammad.

Dear Professor  Ivanova,

I want to optimize this structure using a mixture of solvent (water/DMF = 60:40) and it is greatly appreciated if you and other friend and professors express their kind comments and helps over this question?

See the input file

%chk=C:\Users\ADMIN\Desktop\dmf.chk

# opt hf/3-21g scrf=(cpcm,solvent=n,n-DiMethylFormamide,read)

Title Card Required

0 1

C -1.88188565 0.77433627 0.00000000

C -0.48672565 0.77433627 0.00000000

C 0.21081235 1.98208727 0.00000000

C -0.48684165 3.19059627 -0.00119900

C -1.88166665 3.19051827 -0.00167800

C -2.57926765 1.98231227 -0.00068200

H -2.43164465 -0.17798073 0.00045000

H 0.06278235 -0.17817673 0.00131500

H 1.31049235 1.98216727 0.00063400

H 0.06335835 4.14273927 -0.00125800

H -2.43178865 4.14279927 -0.00263100

H -3.67887165 1.98249527 -0.00086200

eps=36.71

rsolv=2.647

density=0.00778

epsinf=1.75

Dear Prof. Ivanova, 

when you said

"

To these parameters you can add, other, explicitly important ones, which to be taken into account for, too (output below):

-Molar volume [cm**3/mol];

-Thermal expansion coefficient [K**-1];

- Absolute temperature [K] (by default T = 298.15);

- Numeral density [Ang**-3];

- Hydrogen bond acidity;

- Hydrogen bond basicity;

- Surface tension at interface [(cal/mol)*Ang**-2];

- Carbon aromaticity;

- Electronegative halogenicity.

"

what are the keywords for the gaussian input files for these parameters, i can't seem to be able to find examples of the input for these. Are these as given in your answer:

"

Solvent : Generic,

Eps = 37.200000

Eps(infinity) = 2.000000

RSolv = 2.500000 Ang.

Molar volume = 0.000000 cm**3/mol

Thermal expansion coefficient = 0.000000 K**-1

Absolute temperature = 298.150000 K

Numeral density = 0.000000 Ang**-3

Hydrogen bond acidity = 0.000000

Hydrogen bond basicity = 0.000000

Surface tension at interface = 0.000000 (cal/mol)*Ang**-2

Carbon aromaticity = 0.000000

Electronegative halogenicity = 0.000000

"

will the keyword jus be these? Thank you for your kind attention and time!

could you