Harmonic Wavenumbers Research Articles

Thermo- and soluto-capillary convection and instability near the air–liquid interface

Steady thermo- and solute-capillary convection, instability, and pattern evolution near the air–liquid interface driven by point heat and mass sources are investigated. First, under the assumption of the conically similar viscous flow, an exact axi-symmetric solution of the steady thermo- and soluto-capillary convection near the air–liquid interface is determined due to the constant heat and mass fluxes. It is shown that the constant heat, mass fluxes, and the radial surface tension cause the divergent motion at the interface and the Marangoni convection beneath the interface. Then, the linear stability of the steady thermo- and soluto-capillary convection in response to the azimuthal disturbance is analyzed. At a given Peclet (or Schmidt), Marangoni (or Prandtl), and elasticity numbers, the steady basic flow loses its stability when Reynolds number is beyond the critical value. It is found that for small Schmidt numbers, a half-loop structure between the critical Reynolds number and the harmonic wave number of the azimuthal disturbance appears. For large Schmidt numbers, the critical Reynolds number monotonously increases as the harmonic wave number increases. The critical patterns of the velocity fields and the isothermal, iso-concentration lines in the three-dimensional flow system in response to the disturbance harmonic wave number are dominated by both the radial and azimuthal surface tensions. The results not only provide a valuable understanding of Marangoni convection and pattern information near the air–liquid interface but also inspire its potential practical applications in the material chemistry and biotechnology.

Crystal Growth, Structural Elucidation, Chemical Reactivity, Topology Exploration (ELF, LOL, AIM, RDG) and NLO Activity of 4-Cumyl Phenol Crystal Using Quantum Chemical Calculation

The main objective of the study is to analyze the structural behavior and NLO activity of 4-cumyl phenol by experimental and theoretical spectroscopic techniques. Its computational result is compared with the cumene compound. The optimized structural parameters of the title compound were computationally obtained at the B3LYP/6-31G (d, p) basis set. The fundamental modes of vibration were examined by experimental FT-IR, and FT-Raman techniques. The distribution of the vibrational bands was carried out with the help of normal coordinate analysis (NCA). The resulting harmonic wavenumbers were scaled by using NCA method. Topological analysis, such as Electron localization function (ELF), natural bond orbital analysis (NBO), reduced density gradient (RDG) and atoms in molecule (AIM) analysis, molecular electrostatic potential (MEP) have been used to evaluate the intermolecular interaction, especially the hydrogen bonds. UV-visible spectrum of the compound was recorded in the region 200–900 nm and the electronic properties and HOMO-LUMO energies were calculated by time dependent density functional theory approach.

The effects of conformation and intermolecular hydrogen bonding on the structure and IR spectra of flutamide; a study based on the matrix isolation technique, ab initio and DFT calculations

In this study, stable conformers of flutamide referred to as an anticancer drug were searched through a relaxed potential energy surface scan carried out at the B3LYP/6-31G(d) level of theory. This was followed by geometry optimization and thermochemistry calculations performed with the HF-SCF, MP2, B3LYP methods and the 6-31G(d), 6–311++G(d,p), aug-cc-pvTZ basis sets for each of the determined minimum energy conformers. The results revealed that flutamide has at least five stable conformers and two of them provide the major contribution to the observed matrix isolation infrared (IR) spectra of the molecule. The effects of conformational variety and intermolecular hydrogen bonding interactions on the observed IR spectra of flutamide were interpreted in the light of the vibrational spectral data obtained for the most stable monomer and dimer forms of the molecule at the same levels of theory. Pulay’s “Scaled Quantum Mechanical-Force Field (SQM-FF)” method was used in the refinement of the calculated harmonic wavenumbers, IR intensities and potential energy distributions. This scaling method which proved its superiority to both anharmonic frequency calculations and other scaling methods helped us to correctly interpret the remarkable differences between the matrix IR spectra of flutamide in argon and the condensed phase IR spectra of the molecule in solvents such as KBr, H2O, D2O, ethanol and methanol.

Global modes of variable-viscosity two-phase swirling flows and their triadic resonance

The linear and nonlinear dynamics of two-phase swirling flows produced by the Grabowski–Berger profile under the influence of a viscosity stratification are investigated. We perform axisymmetric nonlinear simulations and fully three-dimensional linear global stability analysis of the flow for several swirl numbers $S$ and viscosity ratios $\tilde {\mu }$ . They are accompanied by nonlinear three-dimensional simulations and subsequent modal analysis using the bispectral mode decomposition, recently introduced by Schmidt (Nonlinear Dyn., vol. 102, issue 4, 2020, pp. 2479–2501). We find a pronounced destabilising effect of the viscosity stratification on both the onset of axisymmetric vortex breakdown and helical instability that is linked to the required shear stress continuity across the interface. Consequently, destabilisation is shifted to lower $S$ as compared with an equivalent flow with uniform viscosity. Further, the stability analysis reveals the simultaneous destabilisation of two global modes with wavenumbers $m=1$ and $m=2$ that have harmonic frequencies. The analysis of the nonlinear flow reveals a strong triadic resonance between these modes that governs the nonlinear dynamics and leads to a rapid departure from the linear dynamics. At larger swirl, the bifurcation of additional modes initiates an interaction cascade by means of triadic resonance which is elucidated by the bispectral analysis. It leads to the emergence of a variety of additional modes in the nonlinear flow. This study contributes to an improved understanding of the influence of viscosity stratification on the onset of vortex breakdown and the destabilisation of global modes. Further, it provides a clear picture of the dynamics of swirling flows with a codimension-two point and related triadic interaction of two global modes at harmonic frequencies and wavenumbers.

Normal-Mode Vibrational Analysis of Weakly Bound Oligomers at Constrained Stationary Points of Arbitrary Order.

Following the full realization of the importance of noncovalent interactions, finding and characterizing stationary points (SP), of various order, for weakly bound oligomers have become important tasks for computational chemists. An efficient algorithm and an associated computer code, called oligoCGO, are described, facilitating constrained geometry optimization of oligomers of arbitrary structure and complexity and normal-mode vibrational analysis at nonstationary geometries. To minimize the adverse effects of nonzero forces on harmonic vibrational analyses at constrained stationary points (cSP), two residual gradient correction (RGC) schemes are proposed. RGC1, for which a rigorous justification is given, is based on ignoring the remaining forces in internal-coordinate space. RGC2 modifies the geometry of the cSP in a single Newton step and recalculates the Cartesian Hessian at this updated geometry. As demonstrated by 10 examples related to the water-water, water-methane, and methane-methane dimers as well as the methane trimer, without RGC the harmonic analysis of cSPs may result in even qualitatively incorrect results when compared to reference values obtained at the nearby unconstrained SPs (uSP). Both RGC protocols work exceedingly well, and the corrected harmonic wavenumbers of the cSPs are very close to their uSP counterparts.

Spectroscopic analysis, DFT studies and molecular docking of 2,3‐dichloro‐benzylidine‐(2‐trifluoromethyl‐phenol)‐amine

Abstract2,3‐dichloro‐benzylidine‐(2‐trifluoromethyl‐phenol)‐amine (2DBTP) has been synthesized and characterized by various spectroscopic techniques including FT‐IR, FT‐Raman, UV‐Vis and 1H, 13C NMR spectroscopy. The equilibrium geometry and harmonic vibrational frequencies were investigated by density functional theory (DFT) at B3LYP/6‐311++G(d,p) basis set. The vibrational wavenumber assignments were made on the basis of total energy distribution (TED) calculations using Veda 4 program. The harmonic wavenumbers calculated at DFT were in line with the experimental values. The non‐linear optical properties (NLO) were calculated. Stability of the molecule arises from hyperconjugative interactions and charge delocalization was analyzed by natural bond orbital (NBO) analysis. Molecular electrostatic potential (MEP), mulliken atomic charges were also calculated. The energy gap of the molecule was found by HOMO and LUMO calculation. TD‐DFT calculations have been carried out on the optimized geometry to further understand the electronic transitions in the UV‐Vis spectrum of the compound. In addition, the 1H and 13C NMR chemical shift values of 2DBTP in the ground state were also calculated using Gauge invariant atomic orbital (GIAO) method. The molecular docking solved the binding mode of 2XCT complex with the ligand. The investigated molecule revealed the inhibition activity of the ligand against anti‐bacterial protein topoisomerase DNA gyrase enzyme (PDB ID: 2XCT).

Analytical solution of the nonlinear equations of acoustic in the form of Gaussian beam

The nonlinear acoustics equation for a dissipative medium is analytically solved. Continuous wave stimulation and an axisymmetric Gaussian spatial profile of the boundary conditions were assumed. The approximation of the D'Alambert operator by the wave diffusion operator was applied and justified. In this approximation and assuming classical absorption (dispersion), the equation to be solved is presented by the Khokhlov-Zabolotskaya-Kuznetsov model.A sequence of functions describing the spatial distribution of the harmonic components of the disturbance was determined. They are the form of spatially modulated Gauss functions for harmonic wave numbers (frequencies).For a lossless medium a universal numerical sequence describing non-linear interactions and harmonic generations was determined. In other cases, the description of the cooperation of dispersion and non-linear interactions in the harmonic generation process is given by a sequence of functions dependent on the dispersion coefficient and with boundary values given by the universal sequence mentioned above.It was unexpectedly discovered that the influence of geometrical parameters of the beam on nonlinear interactions depends on dispersion, and component of the dispersion, absorption may strengthen harmonic generation. In general, dispersion spatially modulates the amplitude and phase of nonlinear interactions. This is not against the law of conservation of energy. The energy exchange between the fundamental (initiating) component and other harmonics is described.The analytical solution was compared with the numerical one. The numerical solution was obtained in the scheme implementing the full Helmholtz operator (no axial - wave diffusion- approximation).

Synthesis, crystal structure, spectroscopic, quantum chemical investigation, molecular docking and ADMET prediction of 2(E)-3-(anthracen-9-yl)-1-(1-methyl-1H-pyrrol-2-yl) prop-2-en-1-one

In the present study, 2(E)-3-(anthracen-9-yl)-1-(1-methyl-1H-pyrrol-2-yl) prop-2-en-1-one (3AMP) crystal was grown by slow evaporation method. The single crystal X-ray diffraction analysis and density functional theory (DFT) calculations were carried out for 3AMP crystal. The 3AMP crystallizes in orthorhombic space group Pbca with a = 14.818 (8) Å, b = 9.796 (5) Å, c = 23.239 (11) Å. Hirshfeld surface and finger print plots were analyzed to confirm the existence of intra-, inter-molecular and other weak interactions using Crystal Explorer. The optimized molecular structure and harmonic wavenumbers were calculated by DFT method using B3LYP functional with 6-31G(d,p) basis set. The FT-IR, 1H, 13C NMR and UV–Vis spectra of 3AMP were recorded and analyzed. The optimized geometrical parameters, calculated wavenumbers by DFT method were compared with the experimental results. Natural bond orbital (NBO) analysis was carried out to evaluate the intra- and inter-molecular interactions in the crystal. The energy gap for 3AMP was calculated as 3.156 eV. Molecular electrostatic potential (MEP), Mulliken atomic charges and non-linear optical (NLO) properties for the title crystal were calculated. In addition, gauge invariant atomic orbital (GIAO) method was used to calculate the 1H and 13C NMR chemical shifts in the ground state. To obtain the electronic transitions in UV–Vis spectra of the title molecule in DMSO and ethanol solvents, TD-DFT calculations were performed on the optimized geometry. Furthermore, the compound was subjected to in silico ADMET evaluation. Molecular docking study was carried out to determine the interactions of ligand with the protein Hyaluronidase (PDB ID: 1FCQ).

Spectroscopic and quantum chemical computation on molecular structure, AIM, ELF, RDG, NCI, and NLO activity of 4-VINYL benzoic acid: A DFT approach

Vibrational spectral analysis was carried out for 4-Vinyl Benzoic acid (4VBA) by using Fourier transform infrared (FT-IR) and FT-Raman spectroscopy in the range of 400–4000 and 50–3500 cm−1 respectively. The optimized geometrical parameters were computationally obtained at the DFT/B3LYP level of theory. The distribution of the vibrational bands was carried out with the help of normal coordinate analysis (NCA). The resulting harmonic wavenumbers were scaled by using NCA method. 13C and 1H NMR spectra were recorded and 13C and 1H nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. Topological analysis, such as Electron localization function (ELF), natural bond orbital analysis (NBO), reduced density gradient (RDG) and atoms in molecule (AIM) analysis, molecular electrostatic potential (MEP) have been used to evaluate the intermolecular interaction, especially the hydrogen bonds. UV-visible spectrum of the compound was recorded in the region 200–900 nm and the electronic properties and HOMO-LUMO energies were calculated by time dependent density functional theory approach.

Jet cooled laser-induced fluorescence spectroscopy of tantalum monocarbide: Observation of the ground state vibrations and the low-energy states

• The equilibrium vibrational harmonic wavenumber, ω e for the ground state determined • Present ω e is more accurate and smaller by 28% from the earlier reported value • New assignments of the excitation bands • Low-energy excited states observed and tentatively assigned Laser-induced excitation and dispersed fluorescence (DF) spectra of TaC molecule, produced in laser vaporization free-jet apparatus, were studied to investigate the electronic structure. The DF from the earlier reported and newly assigned bands showed the ground state vibrational progression v = 0−3 and 5. Further, the observation and rotational analysis of the hot band from v = 1 of the ground state confirmed the T v = 1 = 769.108 ( 9 ) c m − 1 . The analysis of the vibrational and band origin data yielded the harmonic frequency ω e = 769.1(1) cm −1 for the X 2 Σ + ground electronic state. This value is distinctly different from the earlier reported value of 1064 cm −1 determined from the anion-photoelectron spectroscopy work (Phys. Rev. A 92 (2015) 042503). Additionally, the reasonably intense dispersed fluorescence peaks between the displacement wavenumber 2400 to 5900 cm −1 are tentatively assigned to low-lying states predicted by the earlier ab initio studies.

Structural and Vibrational Properties of Amino Acids from Composite Schemes and Double-Hybrid DFT: Hydrogen Bonding in Serine as a Test Case

The structures, relative stabilities, and vibrational wavenumbers of the two most stable conformers of serine, stabilized by the O-H···N, O-H···O═C and N-H···O-H intramolecular hydrogen bonds, have been evaluated by means of state-of-the-art composite schemes based on coupled-cluster (CC) theory. The so-called "cheap" composite approach (CCSD(T)/(CBS+CV)MP2) allowed determination of accurate equilibrium structures and harmonic vibrational wavenumbers, also pointing out significant corrections beyond the CCSD(T)/cc-pVTZ level. These accurate results stand as a reference for benchmarking selected hybrid and double-hybrid, dispersion-corrected DFT functionals. B2PLYP-D3 and DSDPBEP86 in conjunction with a triple-ζ basis set have been confirmed as effective methodologies for structural and spectroscopic studies of medium-sized flexible biomolecules, also showing intramolecular hydrogen bonding. These best performing double-hybrid functionals have been employed to simulate IR spectra by means of vibrational perturbation theory, also considering hybrid CC/DFT schemes. The best overall agreement with experiment, with mean absolute error of 8 cm-1, has been obtained by combining CCSD(T)/(CBS+CV)MP2 harmonic wavenumbers with B2PLYP-D3/maug-cc-pVTZ anharmonic corrections. Finally, a composite scheme entirely based on CCSD(T) calculations (CCSD(T)/CBS+CV) has been employed for energetics, further confirming that serine II is the most stable conformer, also when zero-point vibrational energy corrections are included.

Nonlinear input/output analysis: application to boundary layer transition

Abstract

Analysis of Electromagnetic Force Ripple in a Bearingless Synchronous Reluctance Motor

A bearingless machine should be designed to maximize the average and to minimize the ripple in the electromagnetic torque and levitating force. In a bearingless synchronous reluctance machine (BSynRM), the complex rotor design and the levitation winding create a rich spatial and temporal spectrum of the magnetic flux density in the airgap, which affects both the torque and force ripple. In this article, a novel method is introduced to compute the electromagnetic forces from the spatial harmonics of the airgap flux density. A new indexing method is introduced to classify the spatial harmonic wavenumbers and temporal harmonic frequencies of the flux density in the electromagnetic force. The proposed model enables the understanding of the spatial harmonic footprint on the temporal frequencies of the electromagnetic force ripple. The study is carried out through finite element simulations, which are verified by prototype measurements.

Prediction of motion accuracy in five degrees of freedom for hydrostatic rotary table with any recess number

An approximate accuracy model in five degrees of freedom has been built to predict the motion accuracy of hydrostatic rotary tables with any recess number. It is found that the amplitudes of total averaging coefficients depend on the basic averaging coefficients, while the frequencies of total averaging coefficients depend on the layout averaging coefficients. The motion accuracies of journal bearing and those of the two thrust bearings are independent of each other. For the hydrostatic rotary table with any recess number [Formula: see text], the harmonic waves of shaft or thrust plates with wave numbers [Formula: see text] = [Formula: see text], [Formula: see text] have a major impact on the radial or tilt motion accuracies, respectively. The harmonic waves of thrust plates with wave number [Formula: see text] = [Formula: see text] have a major impact on the axial motion accuracy. And [Formula: see text] is a non-negative integer. Increasing recess number can improve motion accuracy since the number of harmonic waves of shaft and thrust plates affecting error motions can be reduced. The recommended recess number 6 may be a compromise between structural complexity and motion accuracy. Both the theoretical and experimental studies show that, for the hydrostatic rotary table with recess number 4, the radial run-out is mainly resulted from the third components of shaft roundness errors which is the selective performance of the recess number, while the axial run-out is generally much smaller than the radial run-out. The theory discussed is very important for design of hydrostatic rotary table used widely in precision machine tools.

Revealing radiationless sources with multi-harmonic mantle cloaking

A general formula for the scattering suppression of simultaneous cylindrical harmonic waves is reported for a bare dielectric cylinder. A proper surface impedance condition is imposed at the boundary between dielectric and background regions, revealing a parity-time condition for the internal electromagnetic field in order to be nonradiating. Depending on the maximum number of cylindrical harmonic waves to suppress along the azimuthal variable φ, such surface impedance function profile reveals several higher order nonradiating modes. The determination of is consistent with the degrees of freedom of the scattered fields. Moreover, the multi-harmonic mantle cloaking technique automatically generates radiationless sources suitable for the implementation with metal-dielectric metasurfaces or all-dielectric metamolecules.

Infrared Spectroscopic and Kinetic Characterization on the Photolysis of Nitrite in Alcohol-Containing Aqueous Solutions.

Nitrite is regarded as a potential OH and NO precursor in aqueous solution upon ultraviolet photolysis. A step-scan Fourier-transform interferometer was employed to collect the transient infrared difference spectra upon excitation of the sodium nitrite aqueous solution in the presence of methanol and ethanol upon 355 nm pulsed excitation. The photolytic intermediates were proposed to be NO and NO2 via the direct dissociation from NO2- and the rapid reaction of OH and NO2-, respectively. Coupled with the theoretical calculations of the absolute energies and harmonic wavenumbers of relevant species using B3LYP density functional theory with the C-PCM model to account for the medium effect of H2O, a transient band at 1860-2030 cm-1 could be attributed to dissolved N2O3 isomers that could be quickly generated from NO + NO2. On the basis of the predicted thermodynamics, the reactions of alcohols with N2O3 were less thermodynamically favorable than that of water, resulting in a slightly decelerated depletion rate of N2O3 in alcohol-containing aqueous solution. Comparing the transient population of N2O3 in the absence and presence of CH3OH or C2H5OH, the upper-bound bimolecular rate coefficient of NO or NO2 with alcohols is reported as 7.3 × 103 M-1 s-1 for the first time. The spectroscopic and kinetic evidence of the reactivity of alcohols with NO, NO2, and N2O3 are provided to augment the roles of alcohols and NxOy in solution or in aqueous aerosol photochemistry.

Spectroscopic, quantum chemical, QTAIM analysis, molecular dynamics simulation, docking studies and solvent effect of pyridin-2-yl oxyacetic acid herbicide and its derivatives

The density functional theory calculations and spectroscopic characterization (FTIR, FT- Raman, 1H, 13C NMR and ultraviolet–visible) of the herbicide compound Triclopyr (TCP) on monomeric and dimeric model is carried out. Its computational results are correlated with two pyridine derivative compounds FPA and FOP. The specific solvent effect of monomer with water complexes (TCPW, FPAW and FOPW) formed by hydrogen bonding interactions are investigated at the B3LYP 6-311G (d,p) level. Potential energy surface (PES) scanning of above compounds has been performed to discover the most stable conformer. The distribution of the vibrational bands are carried out with the help of normal coordinate analysis (NCA) and the resulting harmonic wavenumbers are scaled by using Wavenumber–Linear Scaling (WLS) method. The nature of inter and intramolecular hydrogen bonds are analyzed using NBO, QTAIM and Hirshfeld surface analysis. Furthermore herbicidal activity is confirmed on the compounds with molecular docking studies and molecular dynamic simulations (MDS).

Quantum-mechanical study of energies, structures and vibrational spectra of the HF complexed with dimethyl ether

Interaction energies, geometry and vibrational frequencies of the gas-phase HF-dimethyl ether complex were obtained using quantum-chemical methods. Equilibrium and vibrationally averaged geometries, harmonic and anharmonic wavenumbers of the complex were calculated using second-order perturbation theory procedures with B3LYP, B2PLYP-D and MP2 methods with 6-311++G(2df, 2pd) basis set. Quantum-mechanical model describing anharmonic-type vibrational couplings within hydrogen bond was used to explain broadening, fine structure and temperature dependence of the FH stretching IR absorption bands as effect of hydrogen bond formation. Simulations of the rovibrational structure of the FH stretching bands were performed for different temperatures. The results were compared with experimental spectra.

Molecular analyses using FT-IR, FT-Raman and UV spectral investigation; quantum chemical calculations of dimethyl phthalate

Dimethyl phthalate C6H4 (COOCH3)2 (DIMPHT) has been synthesized. To characterize molecular functional groups FT-IR and FT-Raman spectrum were recorded and wavenumbers were assigned accordingly. The optimized geometrical parameters, vibrational assignments, chemical shifts and thermodynamic properties of title compound were computed by ab-initio calculations at Density Functional Theory (DFT/B3LYP) method with 6–311++G(d,p) as basis set. The potential energy curve expresses that DIMPHT molecule has three stable structures. The computational results diagnose the most stable conformer of the DIMPHT as the conformer 2 of the compound. The calculated harmonic wavenumbers of compound were then analyzed in comparison to experimental FT-IR and Raman spectrum. Gauge independent atomic orbital (GIAO) method was used for determining, (1H) and carbon (13C) nuclear magnetic resonance (NMR) spectra of the molecule. Molecular parameters were calculated along with its periodic boundary conditions calculation (PBC) analysis supported by X-ray diffraction studies. The frontier molecular orbital (HOMO, LUMO) analysis describes charge distribution and stability of the molecule which concluded that nucleophilic substitution is more preferred and the mullikan charge analysis also confirmed the same. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) complements with the experimental findings. In addition, molecular electrostatic potential, nonlinear optical and thermodynamic properties of the title compound were performed. Mulliken and natural charges of the title molecule were also calculated and interpreted. The effects of the computations were applied to theoretical spectra of the title compound, which show excellent agreement with observed spectra. The scaled B3LYP/6-311++G(d,p) results show the best arrangement with the experimental values over the other method.

Structural activity (monomer and dimer), spectroscopic analysis, chemical reactivity, fungicidal activity and molecular dynamics simulation of phenyl benzamide fungicides: A combined experimental and theoretical approach

The present study aims to provide deeper knowledge of the structural activity, spectroscopic analysis, chemical reactivity and fungicidal activity of phenyl benzamide fungicides: flutolanil and mepronil based on monomer and dimer model with the aid of experimental and computational methods. The distribution of the vibrational bands are carried out with the help of normal coordinate analysis (NCA). The resulting harmonic wavenumbers are scaled by using Wavenumber Linear Scaling method (WLS). The nature of the hydrogen bonds are characterized by NBO analysis. The evaluated HOMO and LUMO energies indicate the chemical stability of the molecules. The time dependent density functional theory is used to find the various electronic transitions and their nature within the molecule. The molecular orbital contributions are studied by using TDOS spectral analysis. The molecular electrostatic potential (MESP) and global reactivity descriptor parameters are also performed. The 1H and 13C NMR spectra are recorded. The stable conformers of flutolanil and mepronil have been identified by potential energy surface scan analysis. The binding affinity and hydrogen bond interaction between the selected compounds and the target protein are evaluated using molecular docking studies. The pose with highest interaction energy and hydrogen bond interaction is further analyzed using molecular dynamics studies to understand the effect of ligands on conformational changes of protein and the stability of protein ligand complex. The invitro analysis has been performed against two fungal pathogens, Aspergillus niger and Candida albicans.