[(3-Chloro Phenyl) Piprazine 1-Yl]-3-[Oxy (3-Acetamidazole Phenyl) Propane] Is a Hypertensive Drug. Navane Possesses Certain Chemical and Pharmacological Similarities to the Piperazinephenothiazines and Differences from the Aliphatic Group of Phenothiazines. Although Widely Used In the Treatment of Schizophrenia For Several Decades, Thiothixene Is Seldom Used Today In Favor of Atypical Antipsychotics Such As Risperidone. a Complete Assignment of Fundamental Vibration Frequencies Has Been Made, and the Spectra Have Been Interpreted In Detail. the Non-Planar Frequencies Have Been Calculated With the Aid of Force Constants Determined For Related Molecules. the Fundamental Vibrational Frequencies and Intensity of Vibrational Bands Were Evaluated Using Density Functional Theory (Dft) Using Standard B3lyp6-31G Methods and Basis Set Combinations.The Optimized Geometric Structure of (9Z)-N,N-Dimethyl-9-[3-(4-Methylpiperazin-1-Yl)Propylidene]-9H-Thioxanthene-2-Sulfonamide (Thiothixene) Has Been Studied By Using Density Functional Theory (Dft). on the Basis of Ground and Excited State Geometries, the Absorption Spectra Have Been Calculated Using the Dft Method. to Understand the Non-Linear Optical Properties of (9Z)-N,N-Dimethyl-9-[3-(4-Methylpiperazin-1-Yl)Propylidene]-9H-Thioxanthene-2-Sulfonamide (Thiothixene), We Computed Dipole Moment (Μ) ,Using B3lyp Density Functional Theory Method In Conjunction With 6-31G Basis Set.