BALKAN PHYSICS LETTERS

©Bogazici University Press 09 February 2011

BPL, 19, 191015, pp. 137 – 152, (2011)

AB INITIO HARTREE-FOCK AND DENSITY FUNCTIONAL THEORY STUDY ON

CHARACTERIZATION OF 2-NITRO-N-(4- NITROPHENYL) BENZAMIDE

Y. ZALAOGLU

Physics Department, Osmaniye Korkut Ata University,

Osmaniye, TURKEY.

F.KARABOGA

Physics Department, Abant İzzet Baysal University,

Bolu, TURKEY.

G. YILDIRIM

Physics Department, Abant İzzet Baysal University,

Bolu, TURKEY.

C. TERZIOGLU

Physics Department, Abant İzzet Baysal University,

Bolu, TURKEY.

A. SEROL ERTURK

Chemistry Department, Adıyaman University,

Adıyaman, TURKEY.

and

A. TOLGA ULGEN

Electrical and Electronics Engineering Faculty, Sırnak University,

Sırnak, TURKEY.

Abstract. The optimized molecular structures including bond lengths and angels of 2-nitro-N-(4-nitrophenyl) benzamide

molecule were investigated by utilizing ab initio Hartree–Fock (HF) and Density Functional Theory (B3LYP) methods at 6–

31G(d,p) calculation level. All the calculated bond lengths and bond angles were observed to be in good agreement with each

other. Moreover, thermodynamic properties, atomic charges and ultraviolet visible (UV–Vis) spectra were determined and

interpreted for the characterization of the molecule. In addition, not only did we simulate frontier molecular orbitals (FMO)

and molecular electrostatic potential (MEP) but evaluated the transition state and energy band gap clearly.

Key Words: 2-nitro-N-(4-nitrophenyl)benzamide, B3LYP, HF, FMO, MEP

138 BALKAN PHYSICS LETTERS

1. Introduction

Benzamide obtained by the action of ammonia upon chloride of benzoyl, is the simplest aromatic

carboxylic amide and used in the synthesis of various organic compounds. Several kinds of benzamide

derivatives can be also synthesized from anacardic acid and the studies on these molecules increase day by day

owing to the fact that the increased interest in both the biological of these derivatives in the last decades stems

from its remarkable anthelmentic, antihistaminic, antifungal, and antibacterial [1–9]. 2-nitro-N-(4-nitrophenyl)

benzamide from benzamide derivatives undertakes some vital assignments to continue the biological activity

[10]. Thus, it is important to analyze the characterization of 2-nitro-N-(4-nitrophenyl) benzamide for future

studies. In order to support the experimental evidences, the scientists use computational methods which are

reliable to characterize the molecule because of their efficiency and accuracy with respect to the evaluation of a

number of molecular properties [11]. A suitable quantum chemical study is helpful to predict compound

properties economically and to clarify some experiment phenomena insightfully [12]. Hence theoretical studies

are either reliable or useful to identify the molecule. In this respect, the computational researches on compound

properties tend to increase [13–15]. In this study, we calculated the molecular structures using B3LYP/6–

31G(d,p) and HF/6–31G(d,p) basis sets and compared with the experimental data [10,16]. Comparison of

theoretical and experimental data exhibit well correlation confirming the reliability of the methods employed in

this work. Furthermore; after the frontier orbitals and molecular electrostatic potential were visualized, transition

states and energy band gap were determined and interpreted. Thermodynamic properties, UV-Vis spectra and

atomic charges were also mentioned for the molecule. The aim of this study is to not only investigate the

agreement between theoretical data and experimental results but also clarify the characterization of 2-nitro-N-(4-

nitrophenyl) benzamide and show the way to future studies of this molecule.

2. Computational Details

The optimized molecular structures, UV-Vis spectra, atomic charges, thermodynamic properties and

translation energy (HOMO–LUMO) and molecular electrostatic potential (MEP) of the 2-nitro-N-(4-

nitrophenyl) benzamide molecule were investigated using HF [17] and B3LYP [18] methods at 6–31G(d,p) [19]

calculation level. All the computations were performed by using Gaussian 09 program package program with

molecular visualization program [20,21] on the personal computer.

3. Result and Discussion

We determined the molecular geometry, thermodynamic properties, UV-Vis spectra, atomic charges,

potential energy distributions and frontier orbitals for the characterization of 2-nitro-N-(4-nitrophenyl)

benzamide.

3.1. Molecular Geometry

Y.ZALAOGLU et. al.: AB INITIO HARTREE-FOCK... 139

The molecular structure of 2-nitro-N-(4-nitrophenyl) benzamidemolecule was depicted in Fig. 1 along with

labeling and symbolizing by means of schema. Geometric properties of the structure were depicted and

compared with experimental parameters obtained from the X-ray structure analyses of in Table 1. The

experimental results were found to be in good agreement with the theoretical determines for bond lengths and

bond angles. The largest differences of the calculated geometries from the experimental parameters were noted

to be about 0.02 Å (N23–C29) at B3LYP/6–31G(d,p), 0.04 Å (N22–O26) at HF/6–31G(d,p) calculation level for the

bond lengths; 1.140 (C2–N23–C29) at B3LYP/6–31G(d,p) and 1.23

0 (O24–N21–O25) at HF/6–31G(d,p) respectively

for the bond angles. Moreover, errors between the experimental and calculated bond lengths and bond angles of

2-nitro-N-(4-nitrophenyl) benzamide molecule are given in the same table. As can be seen that computations of

DFT level of theory are superior to that of HF method.

3.2. Thermodynamic Properties

Several thermodynamic parameters were performed by using HF and B3LYP with 6–31G(d,p) basis set and

given in Table 2. Scale factors were recommended [22] for an accurate prediction in determining the zero–point

vibration energies and rotational constants. The total energies and the change in the total entropy of the molecule

at room temperature at different theoretical methods were presented. Table 2 demonstrates several

thermodynamic parameters of the molecule without experimental determinations. As seen from the table,

calculations of HF/6–31G(d,p) basis set for energy parameters and rotational constants are close to that of

B3LYP/6–31G(d,p). Although translational and rotational computations are coincide with the entropies and heat

capacities, HF data are generally smaller than DFT ones.

3.3. HOMO and LUMO Analysis

Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) from

frontier molecular orbitals, very important parameters for quantum chemistry, play important role in the electric

and optical properties [23]. We can determine the way the molecule interacts with other species; hence, they are

called the frontier orbitals. HOMO, which can be thought the outermost orbital containing electrons, tends to

give these electrons such as an electron donor. On the other hand; LUMO can be thought the innermost orbital

containing free places to accept electrons [24]. Owing to the interaction between HOMO and LUMO orbital of a

structure, transition state transition of π–π* type is observed with regard to the molecular orbital theory [25].

Therefore, while the energy of the HOMO is directly related to the ionization potential, LUMO energy is directly

related to the electron affinity. Energy difference between HOMO and LUMO orbital is called as energy gap that

is an important stability for structures [26] and given by using four different methods in Table 3. Further, 3D

plots of highest occupied molecular orbitals (HOMOs), lowest unoccupied molecular orbitals (LUMOs),

HOMO–1, HOMO–2, LUMO+1, and LUMO+2 were shown in Fig. 2. According to B3LYP/6–31G(d,p)

calculation level, the energy band gap │(ΔE)│ (translation from HOMO to LUMO) of the title molecule was

140 BALKAN PHYSICS LETTERS

found to be about 0.145 (a.u.) while the band gap was obtained to be about 0.386 at HF/6–31G(d,p) level of

calculation. The highest occupied molecular orbitals were localized mainly on the ring–1 and vicinity of this

ring; in fact no translation appears on both the ring–2 and N21, O24 and O25 atoms. On the other hand, the lowest

unoccupied molecular orbitals were only localized on the ring–2 and slightly N23 and O28 atoms. Moreover, the

HOMO–1 and HOMO–2 orbitals were partially localized on different parts of the title molecule. The HOMO–1

orbitals are only delocalized on the benzen ring–1, while the HOMO–2 orbitals were delocalized on the benzene

ring–2 and O28 atom. Likewise, the LUMO+1 and LUMO+2 orbitals were partially delocalized on different

parts of the molecule. The LUMO+1 orbitals were delocalized on the molecule except for benzene ring–2,

whereas the LUMO+2 orbitals were delocalized on the benzene ring–2 and slightly delocalized on N22, O26 and

O27 atoms. In addition, Lowest MO Eigen value was calculated –19.20 and –20.62 (a.u.) at B3LYP/6–31G(d,p)

and HF/6–31G(d,p) basis sets, respectively. Highest MO Eigen value was also found to be about 4.83 (a.u.) at

B3LYP/6–31G(d,p) and 5.28 (a.u.) at HF/6–31G(d,p) calculation level. The HOMO–1, HOMO–2, LUMO+1

and LUMO+2 Eigen values of the molecule were also depicted in the same table.

3.4. UV-Vis Spectra Analysis

Electronic transitions are usually classified according to the orbitals engaged or to specific parts of the

molecule involved. Common types of electronic transitions in organic compounds are π–π*, n–π* and

π*(acceptor)–π (donor) [27]. In order to understand the electronic transitions of 2-nitro-N-(4-nitrophenyl)

benzamide, theoretical calculations on electronic absorption spectrum, capable of describing the spectral features

of the molecule, were performed in vacuum by TD [28] methods. The calculated visible absorption maxima of λ

which are a function of the electron availability were reported in Table 4. The visible absorption maxima of the

title molecule were corresponded to the electron transition between frontier orbitals (such as translation from

HOMO to LUMO; or HOMO–3 to LUMO+1) by using calculations of molecular orbital geometry. As can be

seen from the table, λmax were arranged in an order from 300 to 334 nm at TD–B3LYP/6–31G(d,p) whereas they

are obtained to change from 228 to 240 nm at TD–HF/6–31G(d,p) calculation level. The results show the

computations of the calculation levels were noted to be close to each other. In addition, oscillator strength values

depicted in the Table 4 were noticed to be close to each other for all translations at the basis sets. The less intense

band centered at 303 (237) nm at B3LYP (HF) basis set is due to the partly forbidden n–π* (HOMO-

3↔LUMO+1) transition. On the other hand, the more intense band (ascribed to an allowed π–π* (HOMO-

1↔LUMO) transition) observed at TD–B3LYP/6–31G(d,p) calculation level was obtained to be about 0.0117 at

300 nm while the maximum computation (the more intense band) at TD–HF/6–31G(d,p) basis set was calculated

to be 0.4669 at 228 nm.

3.5. Atomic Charges

Y.ZALAOGLU et. al.: AB INITIO HARTREE-FOCK... 141

Atomic charges of 2-nitro-N-(4-nitrophenyl)benzamide, calculated by Mulliken method [29,30] at the

B3LYP/6–31G(d,p) and HF/6–31G(d,p) levels of calculation, were given in Table 5. As can be seen from the

table, all the obtained magnitudes are in good agreement with each other. The magnitudes of the carbon atomic

charges were found to be either positive or negative at the basis sets. These magnitudes were obtained to change

between –0.21 and 0.80. Whereas each carbon atom connected to nitrogen atoms has the positive charge

magnitude, C29 connected to oxygen atom has the maximum charge magnitude (0.55 and 0.80 at B3LYP/6–

31G(d,p) and HF/6–31G(d,p) basis sets, respectively). The magnitudes of the other carbon atoms connected to

hydrogen atoms were calculated to be negative value. Moreover, the magnitudes of the hydrogen atomic charges

were arranged in an order from 0.10 to 0.27 at B3LYP/6–31G(d,p) and 0.16 to 0.33 at HF/6–31G(d,p)

calculation level. The maximum charge magnitude of hydrogen atoms was found for H30 atom connected to

nitrogen atom. Like carbon atoms, the magnitudes of nitrogen atomic charges found to be either positive or

negative at the calculation levels were noted to change from –0.61 to 0.38 at B3LYP/6–31G(d,p) and –0.80 to

0.51 at HF/6–31G(d,p) level of calculation, respectively. The minimum charge magnitude of nitrogen atoms was

noted for N23 atom. On the other hand, for oxygen atoms the magnitudes of charges were calculated to change

from –0.46 to –0.38 for DFT and from –0.56 to –45 HF methods. The minimum charge magnitude was obtained

for O28 atom. The results show that:

* All the hydrogen atoms in molecules lost electrons.

* All oxygen atoms in molecules accepted electrons.

* Charge migration to heavy atoms can be related to molecular interactions.

* HF/6–31G(d,p) basis set has more negative magnitudes than the others.

* Computations of B3LYP and HF calculation levels are in good agreement with each other.

3.6. Molecular Electrostatic Potential

At any given point r(x, y, z) in the vicinity of a molecule, the molecular electrostatic potential, V(r) is

defined in terms of the interaction energy between the electrical charge generated from the molecule electrons

and nuclei and a positive test charge (a proton) located at r [31,32]. The molecular electrostatic potential (MEP)

is related to the electronic density and a very useful descriptor for determining sites for electrophilic attack and

nucleophilic reactions as well as hydrogen–bonding interactions [33,34]. In Fig. 3, whereas electrophilic

reactivity was presented by negative (red) regions, nucleophilic reactivity was shown by the positive (blue)

regions of MEP. As seen from the figure, the red region was localized on the oxygen and vicinity of these atoms.

On the other hand, although the blue region was not seen clearly the nucleophilic reactivity of the molecule was

localized on the hydrogen atoms (especially H30 atom). In this respect, the compound is useful to both bond

metallically and interact intermolecularly. This result was also supported by the evidences of charge analyses

part.

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4. Conclusion

In this study, when clarifying the characterization of 2-nitro-N-(4-nitrophenyl) benzamide, we used ab

initio Hartree Fock and density functional theory methods at 6-31G(d,p) calculation level. Optimized geometric

were carried out using HF/6–31G(d,p) and B3LYP/6–31G(d,p) methods and compared with experimental

values. It was found that all the compared data were shown to have a good agreement with each other. This good

agreement is well within the accuracy of computational results. Moreover, after frontier orbitals and molecular

electrostatic potential were visualized, electronic structure and energy band gap of the title molecule were

investigated and interpreted. Atomic charges, thermodynamic properties and UV–Vis spectra were also

determined for the identification of the molecule. In conclusion, all the calculated data and simulations not only

show the way to the characterization of the molecule but also help for the fundamental researches in physics,

chemistry and biology in the future.

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Figure Captions

Figure 1. The molecular structure of 2-nitro-N-(4-nitrophenyl)benzamide

Figure 2. 3D plots of a) the HOMO; b) LUMO; c) HOMO–1; d) HOMO–2; e) LUMO+1 and f) LUMO+2 of 2-

nitro-N-(4-nitrophenyl) benzamide obtained from DFT method (Red regions show the positive phase

while greens present the negative phase).

Figure 3. 3D plots of the molecular electrostatic potential map of 2-nitro-N-(4-nitrophenyl) benzamide obtained

from DFT method ( Red color shows the negative regions while blue color presents the positive

regions of MEP).

Figure 1: The molecular structure of 2-nitro-N-(4-nitrophenyl)benzamide

Y.ZALAOGLU et. al.: AB INITIO HARTREE-FOCK... 145

Figure 2: 3D plots of a) the HOMO; b) LUMO; c) HOMO–1; d) HOMO–2; e) LUMO+1 and f) LUMO+2 of 2-

nitro-N-(4-nitrophenyl) benzamide obtained from DFT method (Red regions show the positive phase while

greens present the negative phase).

146 BALKAN PHYSICS LETTERS

Figure 3: 3D plots of the molecular electrostatic potential map of 2-nitro-N-(4-nitrophenyl) benzamide obtained

from DFT method ( Red color shows the negative regions while blue color presents the positive regions of

MEP).

Table Captions

Table 1. Experimental values and theoretical optimized geometric parameters of 2-nitro-N-(4-

nitrophenyl)benzamide

Table 2. Theoretically computed energies (a.u.), zero–point vibrational energies (kcal mol–1), rotational

constants (GHz), entropies (cal mol–1 K–1) and dipole moment (Debye)

Table 3. Some of the calculated energy values of 2-nitro-N-(4-nitrophenyl) benzamide molecule in its ground

state with singlet symmetry at DFT and HF methods

Table 4. Theoretical electronic absorption spectra values of 2-nitro-N-(4-nitrophenyl) benzamide molecule

Table 5. Atomic charges for optimized geometry of 2-nitro-N-(4-nitrophenyl) benzamide

Y.ZALAOGLU et. al.: AB INITIO HARTREE-FOCK... 147

Table 1: Experimental values and theoretical optimized geometric parameters of

2-nitro-N-(4-nitrophenyl)benzamide

Bond length

(Å)

Calculated DFT

6–31G(d, p)

Calculated HF

6–31G(d, p) aExperimental

bExperimental

C2-N23 1.4033 ± 0.0139 1.4001 ± 0.0171 1.4092 1.4172

C5-N22 1.4646 ± 0.0184 1.4518 ± 0.0114 1.4632 1.4462

C14-N21 1.4734 ± 0.0041 1.4584 ± 0.0128 1.4712 1.4693

N21-O24 1.2281 ± 0.0099 1.1908 ± 0.0315 1.2182 1.2223

N21-O25 1.2311 ± 0.0069 1.1942 ± 0.0301 1.2242 1.2243

N22-O26 1.2317 ± 0.0094 1.1942 ± 0.0350 1.2292 1.2223

N22-O27 1.2326 ± 0.0083 1.1953 ± 0.0299 1.2252 1.2243

N23-C29 1.3779 ± 0.0914 1.3626 ± 0.1067 1.3612 1.4693

O28-C29 1.2176 ± 0.0044 1.1912 ± 0.0240 1.2132 1.2152

C1-C2 1.4074 ± 0.0241 1.3960 ± 0.0127 1.3833

C1-C6 1.3858 ± 0.0024 1.3758 ± 0.0076 1.3834

C1-H7 1.0868 ± 0.1368 1.0758 ± 0.1258 0.9500

C2-C3 1.4065 ± 0.0172 1.3930 ± 0.0037 1.3893

C3-C4 1.3898 ± 0.0015 1.3817 ± 0.0066 1.3883

C3-H8 1.0800 ± 0.2914 1.0681 ± 0.3033 1.3714

C4-C5 1.3934 ± 0.0021 1.3815 ± 0.0098 1.3913

C4-H9 1.0827 ± 0.1327 1.0716 ± 0.1216 0.9500

C5-C6 1.3945 ± 0.0058 1.3838 ± 0.0165 1.4003

C6-H10 1.0824 ± 0.1324 1.0714 ± 0.1214 0.9500

C11-C12 1.3953 ± 0.0030 1.3829 ± 0.0094 1.3923

C11-C16 1.3959 ± 0.0094 1.3867 ± 0.0186 1.4053

C11-H17 1.0854 ± 0.1354 1.0749 ± 0.1249 0.9500

C12-C13 1.3925 ± 0.0028 1.3838 ± 0.0115 1.3953

C12-H18 1.0849 ± 0.1349 1.0742 ± 0.1242 0.9500

C13-C14 1.3927 ± 0.0026 1.3806 ± 0.0147 1.3953

C13-H19 1.0828 ± 0.1328 1.0717 ± 0.1217 0.9500

C14-C15 1.4006 ± 0.4206 1.3889 ± 0.4089 0.9800

C15-C16 1.3991 ± 0.0038 1.3858 ± 0.0095 1.3953

C15-C29 1.5189 ± 0.0046 1.5150 ± 0.0007 1.5143

C16-H20 1.0857 ± 0.1057 1.0750 ± 0.095 0.9800

N23-H30 1.0107 0.9938

148 BALKAN PHYSICS LETTERS

a: Taken f rom Ref. [10] b: Taken f rom Ref. [34]

Bond Angle (0)

Calculated DFT

6–31G(d, p)

Calculated HF

6–31G(d, p) aExperimental

bExperimental

C1-C2-C3 119.94 ± 0.85 119.74 ± 0.65 120.38 119.09

C1-C2-N23 117.17 ± 0.82 116.67 ± 0.32 116.35 116.52

C3-C2-N23 123.29 ± 0.68 123.58 ± 0.39 123.27 123.97

C14-N21-O24 117.76 ± 0.46 117.75 ± 0.47 118.00 118.22

C14-N21-O25 117.89 ± 0.96 117.07 ± 1.78 118.07 118.85

O24-N21-O25 124.93 ± 2.01 125.16 ± 2.24 123.93 122.92

C5-N22-O26 117.68± 0.54 117.81 ± 0.41 117.85 118.22

C5-N22-O27 117.98 ± 0.87 117.67 ± 1.18 118.67 118.85

O26-N22-O27 124.52 ± 1.60 124.52 ± 1.60 123.48 122.92

C2-N23-C29 128.59 ± 1.14 128.40 ± 0.95 127.45

C2-C1-C6 120.67 ± 0.55 120.73 ± 0.61 120.12

C2-C1-H7 119.79 ± 0.21 119.93 ± 0.07 120.00

C6-C1-H7 119.54 ± 0.46 119.34 ± 0.66 120.00

C2-C3-C4 119.49 ± 0.55 119.43 ± 0.49 118.94

C2-C3-H8 119.59 ± 0.29 120.36 ± 1.06 119.30

C4-C3-H8 120.92 ± 0.12 120.20 ± 0.60 120.80

C3-C4-C5 119.86 ± 0.21 119.99 ± 0.34 119.65

C3-C4-H9 120.88 ± 0.68 120.25 ± 0.05 120.20

C5-C4-H9 119.25 ± 0.95 119.76 ± 0.44 120.20

C4-C5-C6 121.41 ± 0.99 121.26 ± 0.84 120.42

C4-C5-N22 119.47 ± 0.01 119.51 ± 0.03 119.48

C6-C5-N22 119.12 ± 1.15 119.23 ± 1.04 120.27

C1-C6-C5 118.83 ± 0.37 118.85 ± 0.39 118.46

C1-C6-H10 121.62 ± 0.92 121.02 ± 0.32 120.70

C6-C5-H10 119.55 ± 0.35 120.13 ± 0.23 119.90

C12-C11-C16 120.24 ± 0.60 120.34 ± 0.50 120.84

C12-C11-H17 120.13 ± 0.27 120.09 ± 0.31 120.40

C16-C11-H17 119.63 ± 0.33 119.56 ± 0.26 119.30

C11-C12-C13 119.83 ± 0.74 119.79 ± 0.70 119.09

C11-C12-H18 120.42 ± 0.62 120.47 ± 0.67 119.80

C13-C12-H18 119.75 ± 0.45 119.74 ± 0.46 120.20

C12-C13-C14 119.21 ± 0.44 119.13 ± 0.52 119.65

C12-C13-H19 121.95 ± 1.25 121.45 ± 0.75 120.70

C14-C13-H19 118.84 ± 0.66 119.42 ± 0.08 119.50

C13-C14-C15 122.17 ± 0.98 122.19 ± 1.00 121.19

C13-C14-N21 117.61 ± 0.51 117.63 ± 0.49 118.12

C15-C14-N21 120.19 ± 0.81 120.15 ± 0.85 121.00

C14-C15-C16 117.59 ± 0.39 117.78 ± 0.20 117.98

C14-C15-C29 123.90 ± 0.34 124.00 ± 0.24 124.24

C16-C15-C29 118.12 ± 0.34 117.95 ± 0.51 118.46

C11-C16-C15 120.96 ± 0.64 120.77 ± 0.45 120.32

Y.ZALAOGLU et. al.: AB INITIO HARTREE-FOCK... 149

Table 2: Theoretically computed energies (a.u.), zero–point vibrational energies (kcal mol–1), rotational

constants (GHz), entropies (cal mol–1 K–1) and dipole moment (Debye)

Parameters B3LYP/6–31(d,p) HF/6–31(d,p)

Total energy -1041.011 -1034.9819

Zero–point energy 131.55 133.16

Rotational constant

0.86 0.88

0.12 0.13

0.12 0.12

Entropy

Total 139.361 135.295

Translational 42.861 42.861

Rotational 34.507 34.456

Vibrational 61.993 57.978

Heat Capacity

Total 64.288 59.419

Translational 2.981 2.981

Rotational 2.981 2.981

Vibrational 58.326 53.457

Dipole Moment 9.3664 10.3045

150 BALKAN PHYSICS LETTERS

Table 3: Some of the calculated energy values of 2-nitro-N-(4-nitrophenyl) benzamide molecule in its ground

state with singlet symmetry at DFT and HF method

Quantity Value

B3LYP/6–31G(d,p) HF/6–31G(d,p)

Lowest MO Eigen value (a.u.) -19.20 -20.62

Highest MO Eigen value (a.u.) 4.83 5.28

The virial (–V/T) 2.0091 2.0017

HOMO (a.u.) –0.251 –0.342

LUMO (a.u.) –0.106 0.044

HOMO–LUMO gap (a.u.), │ΔE │ 0.145 0.386

HOMO –1 (a.u.) –0.278 –0.369

LUMO + 1 (a.u.) –0.280 –0.387

HOMO –2 (a.u.) –0.086 0.062

LUMO + 2 (a.u.) –0.051 0.092

Y.ZALAOGLU et. al.: AB INITIO HARTREE-FOCK... 151

Table 4: Theoretical electronic absorption spectra values of 2-nitro-N-(4-nitrophenyl) benzamide molecule

Calculated, λcal (nm)

TD–B3LYP/6–31G(d,p) TD–HF/6–31G(d,p)

Wave Length

(nm)

Oscillator

Strength

Wave Length

(nm)

Oscillator

Strength Translation

334 0.0001 240 0.0089 HOMO↔LUMO

303 0.0000 237 0.0000 HOMO-3↔LUMO+1

300 0.0117 228 0.4669 HOMO-1↔LUMO

152 BALKAN PHYSICS LETTERS

Table 5: Atomic charges for optimized geometry of 2-nitro-N-(4-nitrophenyl) benzamide

Atom No B3LYP/6–31G(d,p) HF/6–31G(d,p)

C1 –0.14 –0.21

C2 0.35 0.36

C3 –0.10 –0.17

C4 –0.11 –0.10

C5 0.25 0.11

C6 –0.09 –0.09

H7 0.10 0.16

H8 0.15 0.23

H9 0.14 0.22

H10 0.14 0.22

C11 –0.06 –0.12

C12 –0.09 –0.16

C13 –0.09 –0.10

C14 0.25 0.18

C15 –0.01 –0.10

C16 –0.10 –0.14

H17 0.11 0.18

H18 0.12 0.18

H19 0.15 0.23

H20 0.12 0.19

N21 0.38 0.51

N22 0.38 0.52

N23 –0.61 –0.80

O24 –0.38 –0.45

O25 –0.40 –0.47

O26 –0.40 –0.47

O27 –0.40 –0.48

O28 –0.46 –0.56

C29 0.55 0.80

H30 0.27 0.33