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Re^2: Imaginary frequency

Mridula Guin
mridula.guin@gmail.com


Dearv Alex sir,
The magnitude is 33.04 cm-1.Please tell me how to get rid of this negative frequency.

On Mon Jul 20 '15 1:07am, Alex Granovsky wrote
----------------------------------------------
>Hello,

>The excluded frequency is imaginary (this frequency is marked as
>negative in the printout section). This means that your structure
>is not a minimum on a PES but rather is a saddle point on a PES.
>What is the magnitude of the imaginary/negative frequency?

>Kind regards,
>Alex Granovsky
>
>
>On Fri Jul 17 '15 8:33am, Mridula Guin wrote
>--------------------------------------------
>>Dear firefly users
>>During performing frequency calculation, in the thermochemistry section for an optimized geometry I am getting an imaginary frequency which is excluded. My question is whether the structure is stable or not? You can have a look to the part of the logfile below. Please help me to understand this.

>>Thanks in advance..

>>-------------------------------

>>     THERMOCHEMISTRY AT T=  298.15 K

>>     -------------------------------
>>
>>
>>
>> USING IDEAL GAS, RIGID ROTOR, HARMONIC NORMAL MODE APPROXIMATIONS.

>> P=  1.01325E+05 PASCAL.

>> ALL FREQUENCIES ARE SCALED BY   1.00000

>> THE MOMENTS OF INERTIA ARE (IN AMU*BOHR**2)

>>       480.71546     2956.60067     3437.31425

>> THE ROTATIONAL SYMMETRY NUMBER IS  1.0

>> THE ROTATIONAL CONSTANTS ARE (IN GHZ)

>>      3.75084     0.60985     0.52456

>>   1 IMAGINARY FREQUENCY VIBRATION(S) IS(ARE) EXCLUDED

>>     FROM THE FOLLOWING THERMOCHEMICAL ANALYSIS.

>> THE HARMONIC ZERO POINT ENERGY IS (SCALED BY   1.000)

>>        0.127532 HARTREE/MOLECULE    27990.070745 CM**-1/MOLECULE

>>       80.027708 KCAL/MOL              334.835932 KJ/MOL
>>


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