Experimental and Theoretical Spectroscopic Studies ...

Materials Focus Vol. 4, pp. 164–169, 2015 (www.aspbs.com/mat)

Copyright © 2015 by American Scientific Publishers All rights reserved. Printed in the United States of America

Experimental and Theoretical Spectroscopic Studies of Calcium Carbonate (CaCO3 ) Ujval Gupta, Vivek K. Singh, Vinay Kumar, and Yugal Khajuria∗ School of Physics, Shri Mata Vaishno Devi University, Kakryal, Katra 182320, Jammu and Kashmir, India

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ABSTRACT In this paper, we present complete spectroscopic studies of calcium carbonate (CaCO3 ) molecule. The vibrational analysis of the calcium carbonate molecule was performed using fourier transform infra-red (FTIR) spectroscopy in the range 400–4000 cm−1 . Ultraviolet-visible (UV-Vis) spectroscopy was used to study the electronic transition within the molecule. The photoluminescence (PL) spectra were recorded at different exciting wavelengths. The optimized structural parameters, atomic Mulliken charges, vibrational spectra, thermodynamical properties, HOMO–LUMO analysis and other related molecular properties of the CaCO3 have been investigated by Density Functional theory (DFT) using standard B3LYP functional employing 6-311++G(d,p) basis set. Time-dependent density functional theory (TD-DFT) is used to study oscillator strength and excitation energies of CaCO3 . Our results reveal that there is a good agreement between theoretical and experimental values and also with the earlier reported values. KEYWORDS: Fourier Transform Infra-Red (FTIR) Spectroscopy, UV-Vis, Density Functional Theory (DFT), B3LYP, Calcium Carbonate (CaCO3 ).

Delivered by Publishing Technology to: Guest User IP: 124.124.47.116 On: Thu, 09 Jul 2015 07:24:53 medicinally as an inexpensive dietary Calcium (Ca) sup1. INTRODUCTION Copyright: American Scientific Publishers plement or gastric antacid.9 In the pharmaceutical industry, Calcium carbonate (CaCO3 ) is the cheapest commercially it is used as an inert filter for tablets and other pharmaavailable inorganic abundant mineral. Large number of ceuticals. It may be used as a phosphate binder for the common rocks such as limestone, marble and minerals like treatment of hyperphosphatemia (primarily in patients with calcite and travertine) are largely made up of this com1 chronic renal failure).10 Spectroscopic and theoretical studpound, as are pearls, coral, and a number of sea shells. It ies particularly to study molecular structure, vibrational is also the active ingredient in agricultural lime. In nature, analysis, and thermodynamical properties of such a funCaCO3 has different crystal polymorphs occurring in as 2 damental molecule are very essential for their applications aragonite, vaterite and calcite forms. Several known minand role in medical field. Since, CaCO3 is one of the major erals containing alkaline-earth cations possess derivative constituents of pancreatic calculi, gallstones and kidney or superstructures based on the calcite or aragonite strucstones, hence the spectral and the thermodynamical studtures. Bio-mineralization of calcite, vaterite and monohy3 ies will be useful in the destruction of such stones, using dro calcite happens during the decay of saguaro cactus. laser lithotripsy. Further calcite-type minerals are oftenly used as model Recently, Ramachandran et al.11 used photoacoustic compounds to investigate the structural sources of optical spectroscopy (PAS) to determine the thermal diffusivity anisotropy.4 Calcite occurs as a biomineral and it happens 5–7 and thermal conductivity of the gel grown single crystals to be the major constituent of pancreatic calculi. It is 8 of CaCO3 . They characterized CaCO3 using single crysalso found as a constituent of gallstones. CaCO3 is also tal X-ray diffraction and density determination. In other used in the purification of iron (Fe) from iron ore in a reports, the results of the FTIR spectra of CaCO3 molecule blast furnace. It is also used as a raw material in the refinparticularly to identify its presence in different kinds of ing of sugar from sugar beet. It is a common ingredient gallstones.12–14 Literature survey reveals that neither quanfor many glazes in its white powdered form. It is used in tum chemical calculations, nor the density calculation have the production of toothpaste and has seen resurgence as been reported, as yet for CaCO3 molecule. a food preservative and color retainer. It is widely used In the present paper, a systematic experimental and theoretical study on CaCO3 molecule has been reported. We ∗ Author to whom correspondence should be addressed. have recorded the FTIR spectrum of CaCO3 molecule. Email: [email protected] The quantum chemistry calculations have been performed Received: 16 February 2015 by using DFT theory employing B3LYP/6-311++G(d,p) Accepted: 18 February 2015 164

Mater. Focus 2015, Vol. 4, No. 2

2169-429X/2015/4/164/006

doi:10.1166/mat.2015.1233

Gupta et al.

Experimental and Theoretical Spectroscopic Studies of Calcium Carbonate (CaCO3 )

basis set to compute optimized geometry, atomic charges, and vibrational frequencies along with IR intensities, reduced masses, force constants for CaCO3 in the ground state. All computational calculations of this molecule have been carried out using Gaussian 0915 software. The vibrational assignments were carried out by using vibrational energy distribution analysis (VEDA) software16 which has not been studied previously. Highest occupied molecular orbital (HOMO) and lowest occupied molecular orbital (LUMO) analysis have also been done to elucidate information regarding charge transfer within the molecule. Thermodynamic properties and molecular properties such as ionization potential, electron affinity, global hardness, electronic chemical potential and global electrophilicity of the optimized structure of calcium carbonate are also calculated.

2. EXPERIMENTAL DETAILS

calculated frequency to improve the agreement between the predicted and observed frequencies. The computed harmonic frequencies in the present study have been scaled by 0.96.

3. RESULTS AND DISCUSSION 3.1. Molecular Geometry The optimized molecular structure of CaCO3 with atom numbering having CS point group symmetry is shown in Figure 1. The global minimum energy obtained by DFT theory employing B3LYP/6-311G(d,p) and 6-311++G(d,p) basis sets for title molecule are −941533566674 and −941548636163 a.u respectively. The difference between two energy values is −0015 au. The calculated optimized structural parameters (bond lengths and bond angles) for this molecule are presented in Table I. Both the basis sets almost give the same values of bond lengths and bond angles.

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Pure CaCO3 sample (purity 99.5% A.R.) obtained in powder from Central Drug House (CDH), New Delhi was used 3.2. Atomic Mulliken Charges in the experiment. The FT-IR spectrum of the title comThe atomic charge values have been obtained by the pound was recorded in transmittance mode in the region Mulliken population analysis.20 Mulliken atomic charges 4000–400 cm−1 . The photoluminescence (PL) spectrum of compound are calculated at B3LYP/6-311G(d,p) and of the title compound was recorded using Cary Eclipse 6-311++G(d,p) levels are tabulated in Table II. The Fluorescence Spectrometer equipped with 150 W xenon atomic charges on Ca and C atoms exhibit positive charges Delivered by Publishing to: Guest User lamp as an excitation source. The UV-Vis absorption was Technology in 09 both the cases. The charge distribution shows that all IP: 124.124.47.116 On: Thu, Jul 2015 07:24:53 recorded by using a Shimadzu UV-VIS-2600 double beam oxygen atoms are negatively charged. The O3 and O5 Copyright: American Scientific Publishers spectrophotometer. All the quantum chemistry calculations atoms have the same values of atomic Mulliken charges. based on DFT have been performed by using Gaussian 09 The value of Mulliken charge for Ca atom is 1.103 and program. 1.178 and for C atom is 0.473 and 0.292 at 6-311G(d,p) and 6-311++G(d,p) basis sets respectively. 2.1. Computational Details DFT calculations have been performed using standard 3.3. FTIR Spectroscopy and Vibrational Analysis 6-311G(d,p) and 6-311++G(d,p) basis set to obtained The main aim of the vibrational analysis is to find the variusing Gaussian 09 program to compute optimized ous modes of the vibration in the molecule. The vibrational geometry, bond lengths, bond angles, atomic charges, frequency calculations were carried out after optimizing HOMO–LUMO, thermodynamic properties, and vibrathe structure of the molecule to its minimum energy. tional frequencies for CaCO3 molecule in the ground state. The title compound with 5 atoms gives (3N-6) 9 vibrational levels in the range 114–1765 cm−1 . To assign a band in a experimental vibrational spectra to the molecular fragments one has to recognize which atom play a dominant role in the normal modes corresponding to a band in calculated spectra. The assignments of all the 9 vibrational bands have been made by the corresponding potential energy distributions (PEDs) using VEDA program. Details of the VEDA and the procedure to calculate PED has been described in detail in Refs. [17, 18]. The vibrational assignments have also been further checked by using Gauss view visualization program19 which is which is often used to verify the normal modes of vibrations. Electron correlations effects, insufficient basis sets to describe the molecular orbital exactly and harmonicity are some of the important factors which affect the vibrational Fig. 1. Atomic numbering scheme of CaCO3 . frequencies. It is therefore, important to scale down the

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Table I. Bond lengths (Å) and bond angles ( ) of the molecule using DFT/6-311G(d,p) and 6-311G++(d,p) basis sets.

Ca1-O3 C2-O3 C2-O4 C2-O5 O3-C2-O4 O3-C2-O5 O4-O2-O5 Ca1-O3-C2

Bond lengths 6-311G (d,p) 2.06 1.36 1.21 1.36 Bond angles 124.65 110.69 124.66 91.70

Bond lengths 6-311++G (d,p) 2.07 1.36 1.21 1.36 Bond angles 124.62 110.76 124.62 91.92

2925

60

% Transmittance

Structural parameters

70

50

3450

2515 2872

1021 856 713

1794

1082

40 30 20

873

10 1456 0 4000

3500

3000

2500

2000

1500

1000

500

Figure 2 shows the recorded FTIR spectrum of CaCO3 in Fig. 2. Experimental FTIR spectrum of CaCO3 molecule. the spectral range of 4000–400 cm−1 and Figure 3 shows the theoretically calculated FTIR spectrum of CaCO3 reported by Beniash et al.21 The presence of peak at 856 molecule using B3LYP/6-311G(d,p) basis sets only. The cm−1 confirms the presence of aragonite form. These two calculated and experimentally observed frequency values, are the isomorphic forms of CaCO3 and hence are the along with reduced masses, force constants, IR intensities, characteristic bands of CaCO3 . Both isomorphic forms of percentage potential energy distribution and their vibraCaCO3 have been detected in gallstones22 and hence the tional assignments are tabulated in Table III. Experimenabove characteristics peaks may be used to distinguish the tally observed frequencies which are not listed in Table III calcite form and the aragonite form of CaCO3 in gallare separately discussed in the text below. The major bands stones. The other observed bands at 2515, 2872, 2925, identified for CaCO3 molecule were found at 577, 713, −1 are in good agreement with the reports by and 3450 cmGuest Delivered by Publishing User 856, 873, 1021, 1082, 1456, 1794, 2515, 2872, 2925, and Technology to: 12 −1 Kleiner et al. On: Thu, 09 Jul 2015 07:24:53 3450 cm . Our FTIR spectrumIP: is 124.124.47.116 exactly identical with Copyright: the FTIR spectra reported by Kleiner et al.12 American and our Scientific Publishers 3.4. Determination of Density results are also in good agreement. The authors reported −1 The molecular mass and molar volume of the CaCO3 crysthat the bands at 713, 855, 873, 1082, 1481, 1788 cm are tal was calculated theoretically using DFT theory. The denthe characteristic IR bands of CaCO3 molecule. The sharp sity of the molecule was calculated by using following intense band at 873, 1794 cm−1 and the less intense band relation: at 1082 cm−1 have been assigned to the O–C stretching of = MZ/N V (1) CaCO3 molecule as shown in Table III. The characteristic IR band at 1456 cm−1 is due to C–O stretching vibration.12 where, M-molecular weight, Z-number of molecules in The weak bands observed at 577 and 713 cm−1 is due to unit cell, N -Avogadro number and V -volume of the unit the OCO bending. cell. Here, the molecular mass is 99.94733 a.m.u and It is reported that the peak at 712 cm−1 (which is due to the OCO bending) and 875 cm−1 (which is due to the CO2− 100 3 out-of-plane deformation mode) in the IR spectrum confirms the presence of calcite in any material. In our case the same has been observed at 713 cm−1 and 80 873 cm−1 respectively. The band observed at 856 cm−1 is due to the CO2− 60 3 out-of-plane deformation mode of the aragonite which is in good agreement with the results Table II. Mulliken atomic charges of the optimized geometry of CaCO3 molecule calculated at 6-311G(d,p) and 6-311++G(d,p) basis sets. Atom Ca1 C2 O3 O4 O5

166

6-311G(d,p)

6-311++G(d,p)

1103 0473 −0596 −0473 −0596

1178 0298 −0536 −0404 −0536

% Transmittance

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wavenumber (cm–1)

40 20

6–311 + + G (d, p)

0 4000

3500

3000

2500

2000

1500

1000

500

0

Wavenumber (cm–1) Fig. 3. Theoretical FTIR spectrum of CaCO3 using 6-311++G(d,p) basis set. Mater. Focus, 4, 164–169, 2015

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Table III. A comparison of theoretically calculated and experimentally observed Frequencies, VEDA assignments, PED% values, IR intensities, force constants and reduced masses. Experimental frequencies (cm−1 ) 415 437 577 713 856 873 1083 1794

Unscaled frequencies (cm−1 )

Scaled frequencies (cm−1 )

Assignments

PED%

IR intensities (KM/Mole)

Force constants (mDyne/A)

Reduced masses (AMU)

114 365 451 658 760 823 952 1072 1765

110 353 436 636 735 796 920 1036 1706

TORS OCOCa CaO stretch BEND OCaO BEND OCO BEND OCO OUT OOOC O–C stretch O–C stretch O–C stretch

S8-91 S4-80 S7-91 S6-59 S5-83 S9-91 S3-90 S2-69 S1-93

2016 1405 9163 083 7688 2208 9885 41596 72973

013 138 267 410 561 506 832 880 2409

1731 1752 2227 1604 1650 1268 1558 1299 1312

molar volume value is 35.749 cm3 and hence the calculated density () comes to 2.80 gm/cm3 , which is in good agreement with the literature value, of 2.70 gm/cm3, reported by Ramachandran et al.11 using crystallographic data4 for Eq. (1).

500–1400 nm. The present absorption spectrum of CaCO3 is good agreement with the earlier results.23 24 Both the measurements predict a flat response in the wavelength region 350–600 nm. We have also reported the theoretical calculated electronic excitation energies and oscillator lengths and tabulated in Table IV.

The energies of molecular orbital’s (HOMO and LUMO) are very useful for physicists and chemists and are very

Fig. 4. The frontier molecular orbitals (HOMO-1, HOMO, LUMO, LUMO+1) of the CaCO3 molecule. Mater. Focus, 4, 164–169, 2015

Fig. 5.

UV-Vis spectra of CaCO3 molecule.

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3.5. UV-Vis Spectral Analysis 3.6. Thermodynamic Properties The UV-Vis absorption spectrum of CaCO3 molecule has been recorded in powder form using ISR assemThe density functional theory is a well-established and bly attached with Shimadzu UV-2600 Double beam efficient tool to predict various statistical thermodynamic spectrophotometer in the spectral region 190–1400 nm. properties of molecules. The standard thermodynamic Delivered by Publishing Technology to: Guest User Figure 5 shows the absorption spectrum of the CaCO3 functions such 07:24:53 as total energy (thermal), vibrational IP: 124.124.47.116 On: Thu, 09 Jul 2015 in the spectral region 190–1400 nm. Copyright: In the insetAmerican of the Scientific energy, zero point vibrational energy, heat capacity, Publishers Figure 5 parts of the absorption spectrum in the spectral entropy, rotational constants, dipole moment (Debye) region 200–350 nm and 400–600 nm have also been shown are calculated at B3LYP/6-311G(d,p) and B3LYP/6for the clear view of the absorption peaks. The absorp311++G(d,p) basis sets respectively which are listed in tion peaks observed are at 220, 252, 314 and 460 nm. Table V. The difference in the values calculated by both Our experimentally observed peaks are in good agreement the methods is only marginal. All the thermodynamical with the theoretical values which are tabulated in Table IV. parameters calculated here give available information for The peaks observed at 252 nm and 460 nm are compathe further studies on the CaCO3 molecule. rably broader than the peaks at 220 nm and 314 nm. We have also observed a flat response in the wavelength region 3.7. Frontier Molecular Orbital Analysis

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Table IV. Comparison of experimental and theoretical electronic absorption spectra values of CaCO3 molecule. Wavelength (nm) Theoretical

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404.87 305.24 250.69 231.87

Experimental

Excitation energies (eV) (Theoretical)

Oscillator strengths (f) (Theoretical)

460 314 252 220

3.0623 4.0619 4.9457 5.3472

0.0022 0.0000 0.0004 0.0050

the eventual charge transfer interaction within the molecule and in determining molecular electrical transport properties. Both the HOMO and LUMO orbitals are the main orbital that take part in chemical stability. The HOMO energy is directly proportional to the ionization potential (I = −EHOMO ) and LUMO energy is directly proportional to the electron affinity (A = −ELUMO ). The hardness corresponds to the gap between the HOMO and LUMO orbital energies. The larger the HOMO–LUMO energy gap the harder the molecule. The global hardness, = 1/2ELUMO –EHOMO ). The hardness has been associated with the stability of chemical system. The electron affinity can be used in combination with ionization energy to give electronic chemical potential, = 1/2EHOMO + ELUMO ). The global electrophilicity index, = 2 /2 is also calculated and all these molecular properties above are listed in Table V.

important terms in quantum chemistry.25 The HOMO represents an ability to donate an electron where as LUMO represents the ability to gain an electron. The HOMO energy is directly proportional to the ionization potential and the energy of the LUMO is directly proportional to the electron affinity. The plots of energies of four important molecular orbitals are shown in Figure 4. The HOMO is located at −587 eV over the entire 3.8. Photoluminescence (PL) Spectroscopy molecule and LUMO is at −298 eV which shows that Figure 6 shows the photoluminescence (PL) spectra of charge transfers occur within the molecule. The energy CaCO3 powder at excitation 250 nm and 400 nm. Nedfydifference between the HOMO and LUMO orbital is odova et al.23 has studied the optical properties of calcite −289 eV and is called HOMO–LUMO gap that is an single crystal and observed a luminescent peak at 330 nm, important stability for structures. It is seen from the at 5 eV (∼247 nm) excitation. However, in the CaCO3 Table V that as we go towards the higher basis set the powder intense peaks at 343, 362, 425, and 443 nm (emisvalues of the all the frontier molecular orbitals and other 250 nm) are observed. In addition to these, sion at to: ex = Delivered by Publishing Technology Guest User molecular properties increases. IP: This124.124.47.116 energy gap explains few less intense peaks On: Thu, 09 Jul 2015 07:24:53have also been observed at 380, Copyright: American Scientific Publishers Table V. Calculated thermodynamic and molecular parameters with B3LYP method using 6-311G(d,p) and 6-311++G(d,p) basis sets. Thermodynamic parameters

B3LYP/6-311G(d,p)

Self Consistent Field (SCF) energy Total energy (Thermal), Etotal (Kcal mol−1 ) Vibrational energy, Evib (Kcal mol−1 ) Zero point vibrational energy, E0 (Kcal mol−1 ) Heat Capacity, Cv (Cal/Mol-Kelvin) Entropy, S (Cal/Mol-Kelvin) Rotational Constants (GHZ) A B C Dipole moment (Debye) x y z total Molecular parameters ELUMO+1 (eV) ELUMO (eV) EHOMO (eV) EHOMO−1 (eV) ELUMO –EHOMO (eV) Ionization potential (I) Electron affinity (A) Global hardness () Chemical potential () Global Electrophilicity () Molecular mass (a.m.u) Molecular volume (cm3 /mol)

−941533566674 12863 11086 1004704 13746 71448

168

1260280 278930 228383 00002 −130805 00000 130805 −080 −285 −554 −645 269 554 285 1345 4195 654 9994733 31777

B3LYP/6-311++G(d,p) −941548636163 12785 11007 995156 13811 71596 1262043 276049 226505 −00080 −138672 00000 138672 −108 −298 −587 −678 289 587 298 1445 4425 678 9994733 35749

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References and Notes

429 nm

250

547 nm 569 nm

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529 nm

459 nm 487 nm

425 nm 443 nm

343 nm 362 nm

PL Intensity (arb. units)

1. E. Foran, S. Weiner, and M. Fine, Biogenic Fish-gut Calcium Carbonate is a Stable Amorphous Phase in the Gilt-head Seabream, 200 Sparus aurata, 3: 1700, doi: 10.1038/srep01700. Emission at λex = 400 nm 2. S. R. Kamhi, Acta Cryst. 16, 770 (1963). 3. A. J. Garvie, Laurence, Am. Mineral. 88, 1879 (2003). 150 4. E. N. Maslen, V. A. Streltsov, and N. R. Streltsova, Acta Cryst. B49, 636 (1993). 5. H. G. Begger, A. L. Warshaw, D. L. Carr-Locke, J. P. Neoptolemos, 100 C. Russell, and M. G. Sarr (eds.), The Pancreas, Blackwell Scientific Publications, London (1998). 6. J. Geevarghese, Calcific Pancreatitis: Causes and Mechanisms in the 50 Tropics Compared to Subtropics, I edn., Varghese Publishing House, Bombay (1976). 7. A. C. Schulz, P. B. Morre, P. J. Geevarghese, C. S. Pitchumoni, 0 300 350 400 450 500 550 600 650 700 750 Digest, Disease and Sci. 31, 476 (1986). 8. W. Meier and H. Moernke, Naturwiss. 48, 521 (1961). Wavelength (nm) 9. “Calcium Carbonate”. Medline Plus. National Institutes of Health. Fig. 6. Photoluminescence (PL) spectra of CaCO3 molecule at different 2005-10-01. Archived from the original on 2007-10-17. Retrieved excitation wavelengths (250 and 400 nm). 2007-12-30 10. Herbert A. Lieberman, L. Lachman, and J. B. Schwartz, Pharmaceutical Dosage Forms: Tablets, Dekker, New York (1990), pp. 153, 394, 406, and 459 nm. Luminescence is a surface pheISBN 0-8247-8044-2. nomenon. Powder has more surface area compared to its 11. E. Ramachandran, P. Raji, K. Ramachandran, and S. Natarajan, crystal form. The presence of above peaks may be due to Cryst. Res. Technol. 41N, 64 (2006). 12. O. Kleiner, J. Ramesh, M. Huleihel, B. Cohen, K. Kantarovich, more luminescent center/defects on its large surface area C. Levi, B. Polyak, R. S. Marks, J. Mordehai, Z. Cohen, and in comparison to single crystal.26 In the PL spectrum of S. Mordechai, BioMed Central: BMC Gastroenterology 2, 3 (2002). the same molecule (emission at ex = 400 nm), intense 13. R. Ganapathi Raman and R. Selvaraju, Romanian J. Biophys. 18, 309 peaks observed are at 429, 487, and 547 nm. In addition (2008). 14. T. Qiao, R.-H. Ma, X.-B. Luo, L.-Q. Yang, and Z.-L. Luo, Plos One to these bands few more less intense bands have also been Delivered by Publishing Technology to: Guest User 8, e74887. (2013). observed at 443, 459, 529, and 569 This fluorescence IP:nm. 124.124.47.116 On: Thu, 09 Jul 2015 07:24:53 15. M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. will be useful for Scientific study of CaCO3 is very fundamental and Copyright: American Publishers Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G. A. its further spectroscopic study and applications. Petersson, H. Nakatsuji, M. Caricato, X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng, J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, 4. CONCLUSIONS Y. Honda, O. Kitao, H. Nakai, T. Vreven, Jr. J. A. Montgomery, J. E. Peralta, F. Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers, K. N. In the present paper work, we have thoroughly analyzed Kudin, V. N. Staroverov, R. Kobayashi, J. Normand, K. Raghavachari, the molecular structure, atomic Mulliken charges, density A. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi, N. Rega, calculation, thermodynamic parameters, UV-Vis analysis, N. J. Millam, M. Klene, J. E. Knox, J. B. Cross, V. Bakken, photoluminescence study, HOMO–LUMO energy gaps C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, and other molecular properties of the optimized geomeA. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, R. L. Martin, K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salvador, J. J. try of the CaCO3 molecule by using DFT theory using Dannenberg, S. Dapprich, A. D. Daniels, Ö. Farkas, J. B. Foresman, B3LYP/6-311++G(d,p) basis set. Vibrational spectra of J. V. Ortiz, J. Cioslowski, and D. J. Fox (2009), Gaussian, Inc., the title molecule were studied both experimentally and Gaussian 09, Revision A, 1, Wallingford, CT (2013). theoretically and the results obtained showed good agree16. M. H. Jamroz, Vibrational Energy Distribution Analysis VEDA 4, ment with each other. The assignments of the wave numWarsaw (2004). 17. M. H. Jamroz, Jan Cz. Dobrowolski, and R. Brzozowski, Journal of bers have been made by the corresponding PEDs. The Molecular Structure 787, 172 (2006). PED calculation confirms the reliability and accuracy of 18. M. K. Jamroz, M. H. Jamroz, Jan Cz. Dobrowolski, Jan A. Glinski, the vibrational spectral analysis and confirming the present and M. H. Davey, Spectrochmica Acta Part A 78, 107 (2011). assignments. Hence, FTIR spectroscopy can be used to 19. A. Frisch, A. B. Neilson, and A. J. Holder, Gaussview User Manual, Gaussian Inc. Pittsburgh, PA (2000). determine the presence of CaCO3 in pancreatic stones, 20. R. S. Mulliken, J. Chem. Phys. 23, 1833 (1955). gallstones and kidney stones and hence its role in the 21. E. Beniash, J. Aizenberg, L. Addadi, and S. Weiner, Proc. R. Soc. pathogenesis of these stones. Further thermodynamical London Ser. B 264, 461 (1997). parameters can be used effectively in the lithotripsy tech22. A. J. Harding Rain, Gallstones: Causes and Treatments, William niques to destroy these stones. Heinemann Medical Books, London (1964). 23. I. V. Nefyodova, N. I. Leonyuk, and I. A. Kamenskikh, J. Opt. Adv. Mat. 5, 609 (2003). Acknowledgments: Financial assistance from Sci24. The article can be found at:http://www.crystaltechno.com/Materials/ ence and Engineering Research Board (SERB), DST, CaCO3.htm New Delhi (SR/S2/LOP-0020/2012) is gratefully 25. K. Fukui, T. Yonezawa, and H. Shingu, J. Chem. Phys. 20, 722 (1952). acknowledged. 26. P. A. Rodnyi and I. V. Khodyuk, Opt. Spectro. 111, 776 (2011). Emission at λex = 250 nm