Dunning's Correlation Consistent Basis Research Articles

Formation Mechanism of the Unsubstituted Chlorophosphazene Cl3P═NH: A Theoretical Study via Quantum Mechanical Calculations.

Although the synthesis of chlorophosphazene polymers has been explored for more than 100 years, the shortest yet most illusive monomer, Cl3P═NH, has never been isolated and fully characterized. Here we investigate the formation of Cl3P═NH from PCl5 and NH3 in chlorobenzene through quantum mechanical calculations. The potential energy surface was mapped using the MP2 Hamiltonian in conjunction with Dunning's correlation-consistent basis sets (aug-cc-pVXZ, where X = D and T). Along with HOMO/LUMO frontier molecular orbitals and natural bond orbital analyses, we found that instead of following the SN1 path proposed in the literature, the reaction proceeds via an addition-elimination mechanism. Our results also indicate that due to the low-lying stable intermediates (IM), most steps are exothermic such that the production of Cl3P═NH·2HCl can be completed once the energy barrier for the formation of [PCl4-NH3]+Cl- is overcome. Therefore, our theoretical work might explain the challenges in isolating any of the IMs in a typical chlorophosphazene reaction in chlorobenzene.

Accurate ab initio potential energy surface, rovibrational energy levels and resonance interactions of triplet ( 3 B1 ) methylene.

In this work, we report rovibrational energy levels for four isotopologues of methylene (CH2 , CHD, CD2 , and 13 CH2 ) in their ground triplet electronic state ( 3 B1 ) from variational calculation up to ~10,000 cm-1 and using a new accurate ab initio potential energy surface (PES). Triplet methylene exhibits a large-amplitude bending vibration and can reach a quasilinear configuration due to its low barrier (~2000 cm-1 ). To construct the ab initio PES, the Dunning's augmented correlation-consistent core-valence orbital basis sets were employed up to the sextuple-ζ quality [aug-cc-pCVXZ, X = T, Q, 5, and 6] combined with the single- and double-excitation unrestricted coupled cluster approach with a perturbative treatment of triple excitations [RHF-UCCSD(T)]. We have shown that the accuracy of the ab initio energies is further improved by including the corrections due to the scalar relativistic effects, DBOC and high-order electronic correlations. For the first time, all the available experimental rovibrational transitions were reproduced with errors less than 0.12 cm-1 , without any empirical corrections. Unlike more "traditional" nonlinear triatomic molecules, we have shown that even the energies of the ground vibrational state (000) with rather small rotational quantum numbers are strongly affected by the very pronounced rovibrational resonance interactions. Accordingly, the polyad structure of the vibrational levels of CH2 and CD2 was analyzed and discussed. The comparison between the energy levels obtained from the effective Watson A-reduced Hamiltonian, from the generating-function approach and from a variational calculation was given.

On the three lowest spin states of Na13+: Hybrid Density Functional Theory and benchmark CASSCF(12,12)+CASPT2 studies

AbstractThe three lowest spin states (S = 0,1,2) of 12 representative isomers have been estudied using both, KS‐DFT via three hybrid density functionals, and benchmark multireference CASSCF and CASPT2 methods with a couple of Dunning's correlation consistent basis sets. CASSCF(12,12) geometry optimizations were carried out. Since 12 electrons in 12 active orbitals span the chemically‐significant complete valence space, the results of the present study provide benchmarks for . The CASPT2(12,12)/cc‐pVTZ* lowest energy structures are three nearly degenerate singlets (S = 0): an isomer formed from two pentagonal bipyramids fused together (PBPb), a capped centered‐squared antiprism [CSAP‐(1,3)] and an optimum tetrahedral OPTET(II) structure, the last two lying 0.88 and 1.63 kcal/mol above the first, respectively. The lowest triplet (S = 1) and quintet (S = 2) states lie 4.33 and 3.77 kcal/mol above the singlet global minimum, respectively. The latter is a deformed icosahedron while the former is a CSAP‐(1,3). The flatness of the potential energy surface of this cluster suggests a rather strong dynamical character at finite temperature. Prediction of the lowest energy structures and electronic properties is crucially sensitive both to non‐dynamical and dynamical electron correlation treatment. The CASPT2 vertical ionization energy is 3.66 eV, in excellent agreement with the 3.6 ± 0.1 eV experimental figure. All the isomers are found to have a strong multireference character, thus making KS density functional theory fundamentally inappropriate for these systems. Only large multiconfigurational CASSCF wavefunctions provide a reliable zeroth‐order description; then the dynamic correlation effects must be properly taken into account for a truly accurate account of the structural and energetic features of alkali‐metal clusters.

Spectroscopic identification of the low-lying electronic states of S2 molecule.

As is well-known, the S2 molecule is a ubiquitous intermediate in the combustion, atmosphere, and interstellar space. The six low-lying bound states of S2 have been characterized via photoelectron velocity map imaging and a high-level multi-reference configuration interaction method with the Davidson correction. Spectroscopic constants have been extracted by fitting the potential energy curves extrapolated to the complete basis set limit with a series of Dunning's correlation-consistent basis sets: aug-cc-pV(Q, 5)Z. The calculated spectroscopic parameters well reproduce the experimental results in this work. On the basis of the theoretical calculations, Franck-Condon simulations are performed to assign six adjacent electronic states, especially for three higher overlapping electronic states (c1Σu -, A'3Δu, and A3Σu +). The dissociation energy De of the S2 - is evaluated to be 4.111 (4) eV in this work, in agreement with the theoretical prediction (4.056 eV).

Improving "Silver-Standard" Benchmark Interaction Energies with Bond Functions.

We investigate the effect of adding midbond basis functions on the performance of various conventional and explicitly correlated (F12) estimates of complete basis set limit coupled-cluster (CCSD(T)/CBS) noncovalent interaction energies. In particular, we search for an improved "silver standard" of interaction energy calculations for systems where the CCSD(T) computation is feasible in a double-ζ basis but not in a triple-ζ one. We follow a recent study ( Sirianni J. Chem. Theory Comput. 2017 , 13 , 86 ) of different CCSD(T)-F12 variants in midbondless bases over the A24 and S22 benchmark interaction energy databases, and extend Dunning's correlation-consistent basis sets with three different midbond sets. The addition of bond functions is highly beneficial for conventional CCSD(T) and most CCSD(T)-F12 variants, improving both the CCSD part and the unscaled triples contribution. However, the commonly used scaling of triples by the ratio of the MP2-F12 and MP2 correlation energies usually overshoots: as a result, the scaled triples term gets worse upon the addition of bond functions. In contrast, a milder triples scaling by the ratio of the CCSD-F12b and CCSD correlation energies ( Brauer , Phys. Chem. Chem. Phys. 2016 , 18 , 20905 ) leads to the most accurate estimates of this term as long as bond functions are included. The combination of the triples term scaled in this way with the CCSD-F12b interaction energy leads to the CCSD(Tbb)-F12b approach that provides consistent high accuracy when a (3 s3 p2 d2 f) set of midbond functions is added to the aug-cc-pVDZ atom-centered basis set. The combination of midbond functions and the composite MP2/CBS+δ(CCSD(T)) treatment is able to make up for the deficiencies in the atom-centered part of the basis set, in particular, for a partial (or even complete) lack of diffuse functions. Considering both the A24 and S22 accuracy and the computational efficiency, we propose several new "silver standard" approaches improving upon the currently established midbondless levels of theory, ranging from the most consistent CCSD(Tbb)-F12b/aug-cc-pVDZ+(3 s3 p2 d2 f) variant (with mean unsigned errors of 0.010 and 0.042 kcal/mol for the A24 and S22 databases, respectively) to the significantly cheaper MP2/CBS+δ(CCSD(T))/cc-pVDZ+(3 s3 p2 d2 f) approach (mean unsigned errors of 0.039 and 0.096 kcal/mol for A24 and S22, respectively).

A Coupled Cluster Investigation of SNO Radical Isomers and Their Reactions with Hydrogen Atom: Insight into Structures, Conformers, Barriers, and Energetics.

High-level coupled cluster theory with single and double excitation, and including a perturbative triples correction (CCSD(T)) method and a series of Dunning's augmented correlation consistent basis sets, aug-cc-pVXZ (X = D, T, Q, and 5) was applied to examine the conformational landscape of SNO radical system. The basis set has an important effect on the relative stability of SNO radical isomers; that is, at the CCSD(T)/aug-cc-pV5Z level of theory, the NSO radical is the most stable member of SNO radical family. This is in contrast to previous density functional theory prediction suggesting SNO radical is the most stable isomer. The CCSD(T)/aug-cc-pV5Z//CCSD(T)/aug-cc-pVTZ results suggest that the reaction between SNO radical isomers and hydrogen atom result in the formation of their [H,N,S,O] hydrides with HNSO hydrides being the most stable ones. Subsequently, these hydrides could decompose either into SH and NO radicals or into SN and OH radicals. The former pathway is preferred due to relatively lower barriers and favorable reaction energies. The results from our calculations support the role of S-nitrosothiols as NO shuttling agent in signaling-pathways and as a new source of HS and NO radicals in the lower atmosphere of Venus. Overall, these high-level calculations will play an important role in improving our understanding about the chemistry of S-nitrosothiols that has recently become a topic of interest because of their involvement in biochemical pathways and planetary processes.

Potential energy surfaces of the electronic states of Li2F and Li2F(.).

The potential energy surfaces of the ground and low-lying excited states for the insertion reaction of atomic fluorine (F) and fluoride (F(-)) into the dilithium (Li2) molecule have been investigated. We have carried out explicitly correlated multi-reference configuration interaction (MRCI-F12) calculations using Dunning's augmented correlation-consistent basis sets. For the neutral system, the insertion of F into Li2 proceeds via a harpoon-type mechanism on the ground state surface, involving a covalent state and an ionic state which avoid each other at long distance. A detailed analysis of the changes in the dipole moment along the reaction coordinate reveals multiple avoided crossings among the excited states and shows that the charge-transfer processes play a pivotal role for the stabilization of the low-lying electronic states of Li2F. For the anionic system, which is studied for the first time, the insertion of F(-) is barrierless for many states and there is a gradual charge transfer from F(-) to Li2 along the reaction path. We also report the optimized parameters and the spectroscopic properties of the five lowest states of the neutral and seven lowest states of the anionic systems, which are strongly stabilized with respect to their respective Li2 + F/F(-) asymptotes. The observed barrierless insertion mechanisms for both systems make them good candidates for investigation under the ultracold regime.

Spectroscopic properties of BCl (X1Σ+, a3Π, A1Π) molecule

The X1Σ+, a3Π and A1Π states of BCl molecule are studied using the highly accurate valence internally contracted multireference configuration interaction approach including the Davidson modification. The Dunning's correlation-consistent basis sets, aug-cc-pV6Z and aug-cc-pV5Z, are used in the study. To obtain more reliable results, the potential energy curves (PECs) of three electronic states are extrapolated to the complete basis set limit by the two-point total-energy extrapolation scheme. The effects of the core-valence correlation and relativistic corrections on the PECs are taken into account. By fitting these PECs, the spectroscopic parameters (Te, Re, ωe, ωexe, Be, αe and De) of the X1Σ+, a3Π and A1Π states of BCl are determined. These parameter values coincide with the experimental results. In addition, the whole vibrational states for X1Σ+, a3Π and A1Π states at J =0 (J is the rotational quantum number) are determined by numerically solving the radical Schrödinger equation of the nuclear motion of diatomic molecules. For each vibrational state, the vibrational level and inertial rotation constants are obtained, which are in excellent accordance with the experimental results. With the potential energy curves obtained at MRCI+Q/56+CV+DK level and the MRCI wave functions, the Franck-Condon factors, radiative lifetime of transition from a3Π and A1Π to the ground state are computed.

Force-field calculation and geometry of the HOOO radical

High-level ab initio calculations using the Davidson-corrected multireference configuration interaction (MRCI) level of theory with Dunning's correlation consistent basis sets and force-field calculations were performed for the HOOO radical. The harmonic vibrational frequencies and their anharmonic constants obtained by the force-field calculations reproduce the IR-UV experimental vibrational frequencies with errors less than 19 cm(-1). The rotational constants for the ground vibrational state obtained using the vibration-rotation interaction constants of the force-field calculations also reproduce the experimentally determined rotational constants with errors less than 0.9%, indicating that the present quantum chemical calculations and the derived spectroscopic constants have high accuracy. The equilibrium structure was determined from the experimentally determined rotational constants combined with the theoretically derived vibration-rotation interaction constants. The determined geometrical parameters agree well with the results of the present MRCI calculation.

High-Level ab Initio Investigations on Structures and Energetics of N2O Clusters

Both experimental and theoretical investigations on weakly bonded small N2O clusters have been a subject of interest for the past decade. The current article presents high-level ab initio calculations for (N2O)n clusters for n = 4-6 employing second-order Møller-Plesset (MP2) theory and coupled cluster singles and doubles with perturbative triple (CCSD(T)) theory using Dunning's correlation-consistent basis sets. The electrostatics-guided cluster building code developed in our laboratory is applied for the generation of initial cluster geometries, followed by geometry optimization at MP2/aug-cc-pVTZ level of theory. Calculations of single point energy at CCSD(T)/aug-cc-pVTZ and vibrational frequency at the MP2/aug-cc-pVTZ level of theory are facilitated by the fragment-based molecular tailoring approach (MTA). A comparison of the results is done with those obtained by employing dispersion-corrected density functional B2PLYPD with aug-cc-pVTZ basis set. The geometrical parameters and vibrational spectra obtained from these ab initio methods are found to be in good agreement with those derived from recent experimental findings of Oliaee et al. [J. Chem. Phys. 2011, 134, 074310] and Rezaei et al. [J. Chem. Phys. 2012, 136, 224308].

Nuclear magnetic resonance shieldings of water clusters: is it possible to reach the complete basis set limit by extrapolation?

We have explored the possibility of using extrapolation techniques to estimate the complete basis set limit of nuclear shieldings of small water clusters. Several density functionals (Becke-Lee-Yang-Parr (BLYP), Perdew-Burke-Ernzerhof (PBE), OPTX-Perdew-Burke-Ernzerhof (OPBE), Swart-Solà-Bickelhaupt functional with Grimme's Dispersion included (SSB-D) and wavefunction methods (Hartree–Fock, Møller-Plesser perturbation theory for electron correlation up to second order (MP2) and coupled cluster) were used in combination with Dunning's (augmented) correlation-consistent and Jensen's polarisation-consistent basis sets. Although density functionals show larger nuclear shieldings than coupled cluster methods for these water clusters, differences in chemical shifts are much smaller. A new extrapolation scheme based on a Gaussian exponential function is shown to achieve better results for reaching the basis set limiting values, but the exponential needed for it cannot be obtained a priori with good confidence. This renders a two-point extrapolation for prediction of the basis set limiting value impossible.

Theoretical characterization of hydrogen pentoxide, H2O5

Following our investigations on hydrogen polyoxides, herein we employed coupled cluster theory in conjunction with Dunning's correlation consistent basis sets and density functional theory to study HOOOOOH (H2O5). The infrared spectra of H2O5 and its three deuterated isotopologues, as well as those of the five single‐substituted 18O isotopologues are discussed in detail. Internal valence coordinates were employed to classify the vibrational modes. The Raman activity is reported to help in the identification of hydrogen pentoxide. The suggested enthalpy of formation is ΔHf,298° (HOOOOH) = 1.4 ± 1.5 kcal/mol. This value includes corrections for relativistic and core‐valence effects as well as anharmonic corrections to Zero‐point energy corrections. © 2013 Wiley Periodicals, Inc.

Correlated ab initio investigations on the intermolecular and intramolecular potential energy surfaces in the ground electronic state of the ${\rm O}_2^ - ({\rm X}{}^2\Pi _{\rm g}) - {\rm HF}({\rm X}{}^1\Sigma^ +)$O2−(XΠg2)− HF (XΣ+1) complex

This work reports the first highly correlated ab initio study of the intermolecular and intramolecular potential energy surfaces in the ground electronic state of the O(2)(-)(X(2)Π(g))-HF(X(1)Σ(+)) complex. Accurate electronic structure calculations were performed using the coupled cluster method including single and double excitations with addition of the perturbative triples correction [CCSD(T)] with the Dunning's correlation consistent basis sets aug-cc-pVnZ, n = 2-5. Also, the explicitly correlated CCSD(T)-F12a level of theory was employed with the AVnZ basis as well as the Peterson and co-workers VnZ-F12 basis sets with n = 2 and 3. Results of all levels of calculations predicted two equivalent minimum energy structures of planar geometry and C(s) symmetry along the A" surface of the complex, whereas the A' surface is repulsive. Values of the geometrical parameters and the counterpoise corrected dissociation energies (Cp-D(e)) that were calculated using the CCSD(T)-F12a/VnZ-F12 level of theory are in excellent agreement with those obtained from the CCSD(T)/aug-cc-pV5Z calculations. The minimum energy structure is characterized by a very short hydrogen bond of length of 1.328 Å, with elongation of the HF bond distance in the complex by 0.133 Å, and D(e) value of 32.313 Kcal/mol. Mulliken atomic charges showed that 65% of the negative charge is localized on the hydrogen bonded end of the superoxide radical and the HF unit becomes considerably polarized in the complex. These results suggest that the hydrogen bond is an incipient ionic bond. Exploration of the potential energy surface confirmed the identified minimum and provided support for vibrationally induced intramolecular proton transfer within the complex. The T-shaped geometry that possesses C(2v) symmetry presents a saddle point on the top of the barrier to the in-plane bending of the hydrogen above and below the axis that connects centers of masses of the monomers. The height of this barrier is 7.257 Kcal/mol, which is higher in energy than the hydrogen bending frequency by 909.2 cm(-1). The calculated harmonic oscillator vibrational frequencies showed that the H-F stretch vibrational transition in the complex is redshifted by 2564 cm(-1) and gained significant intensity (by at least a factor of 30) with respect to the transition in the HF monomer. These results make the O(2)(-)-HF complex an excellent prototype for infrared spectroscopic investigations on open-shell complexes with vibrationally induced proton transfer.

Spectroscopic properties of AlC (X4∑-, B4∑-) molecule

The potential energy curves (PECs) of X4∑- and B4∑- states of the AlC molecule have been studied using highly accurate internally contracted multireference configuration interaction approach with the Davidson modification. The Dunning's correlation-consistent basis sets, aug-cc-pVnZ (n=D,T,Q,5,6) are used for the present study. To improve the quality of PECs, core-valence correlation and scalar relativistic corrections are considered. Core-valence correlation corrections are calculated with an aug-cc- pCVTZ basis set. Scalar relativistic correction calcualtions are made using the third-order Douglas-Kroll Hamiltonian approximation at the level of a cc-pV5Z basis set. Obvious effect on the PECs by the core-valence correlation and relativistic corrections has been observed. All the PECs are extrapolated to the complete basis set limit. The convergence observations of present calculations are made and the convergent behavior is discussed with respect to the basis set. Using these PECs, the spectroscopic parameters (TeReωeωexeωeyeBe and αe) of the X4∑- and B4∑- states are determined and compared with those reported in the literature. The vibration manifolds are evaluated for each state of non-rotation AlC molecule by numerically solving the radial Schrödinger equation of nuclear motion. For each vibrational state, the vibrational level and inertial rotation constants are obtained, which are in excellent accordance with the experimental findings.

Coupled cluster investigation of the axial and equatorial isomers of pyrrolidine

The CCSD(T) methodology coupled with Dunning's correlation-consistent basis sets was employed to study the relative energies of the axial and equatorial pyrrolidine. The enthalpies of formation of both isomers were computed including corrections for relativistic and core-valence effects as well as anharmonic effects. The accurate determination of the lowest energy isomer is a very complex task because of the very small energy gap. At the CCSD(T)/CBS level, equatorial pyrrolidine is 0.10 kcal/mol lower in energy than axial pyrrolidine. When core-valence, scalar relativistic and spin-orbit effects are included, the relative energy is similar, 0.11 kcal/mol. However, when zero-point energies are taken into account, some difficulties are observed. Anharmonic effects on ZPEs were not possible to be accurately estimated as problems were detected in the lowest vibrational modes. Thus, the question of which is the lowest energy isomer of pyrrolidine remains open until accurate ZPEs can be determined for both isomers. The enthalpy of formation of pyrrolidine is predicted to be −2.7 ± 1 kcal/mol at 298 K.

Infinite Basis Set Extrapolation for Double Hybrid Density Functional Theory 2: Effect of Adding Diffuse Basis Functions

AbstractWe applied the Infinite Basis (IB) set extrapolation and Double Hybrid Density Functional Theory (DHDF) to calculate the electron affinities, reaction barrier heights, proton affinities, non‐covalent interactions, atomization, ionization, and alkyl bond dissociation energies. We previously found that the mean unsigned error of the B2KPLYP‐IB calculation with the combination of cc‐pVTZ and cc‐pVQZ reach the chemical accuracy limit (∼2 kcal/mol) where the largest deviation occurred in the electron affinity calculations and the weak interactions between noble gases and nonpolar molecules. Here, we investigated the basis set effect using the B2KPLYP‐IB extrapolation scheme that involves (1) the addition of extra tight d basis functions to the second row elements (i.e. cc‐pV(L+d)Z), (2) the addition of extra s, p, and d diffuse basis functions, and (3) a comparison between Dunning's Correlation Consistent and Jensen's Polarization Consistent (pc‐L) basis sets. We found that the addition of extra s and p diffuse basis functions formed the minimal augmented basis sets proposed by Truhlar. This addition permitted the B2KPLYP‐IB to reach the chemical accuracy limit with the combination of the double ζ and triple ζ basis sets. Adding extra s, p diffuse functions to the pc‐L series permitted only a small improvement. This small improvement is due to the fact that the pc‐L basis sets already contain a large number of functions for the p block elements. Taken together, the results suggest that this minimal augmented basis sets is useful for due to its accuracy and affordable computational cost.

Liquid properties of dimethyl ether from molecular dynamics simulations usingAb Initioforce fields

We have used molecular dynamic simulations to study the structural and dynamical properties of liquid dimethyl ether (DME) with a newly constructed ab initio force field in this article. The ab initio potential energy data were calculated at the second order Møller-Plesset (MP2) perturbation theory with Dunning's correlation consistent basis sets (up to aug-cc-pVQZ). We considered 17 configurations of the DME dime for the orientation sampling. The calculated MP2 potential data were used to construct a 3-site united atom force field model. The simulation results are compared with those using the empirical force field of Jorgensen and Ibrahim (Jorgensen and Ibrahim, J Am Chem Soc 1981, 103, 3976) and with available experimental measurements. We obtain quantitative agreements for the atom-wise radial distribution functions, the self-diffusion coefficients, and the shear viscosities over a wide range of experimental conditions. This force field thus provides a suitable starting point to predict liquid properties of DME from first principles intermolecular interactions with no empirical data input a priori.

Study on spectroscopic properties of B2 (X3g-, A3u) molecule

The X3g- and A3u states of B2 molecule are studied using highly accurate valence internally contracted multireference configuration interaction approach including the Davidson modification. The Dunning's correlation-consistent basis sets, aug-cc-pV6Z and aug-cc-pV5Z, are used in the study. To obtain more reliable results, the potential energy curves (PECs) of two electronic states are extrapolated to the complete basis set limit by the two-point total-energy extrapolation scheme. The effects of the core-valence correlation and relativistic correction on PEC are taken into account. Employing these PECs, the spectroscopic parameters (Te, Re, e, exe, eye, Be, e, e and e) of the X3g- and A3u states of two main isotopes (11B2, 10B11B) are determined and compared with those reported in the literature. Comparison with the experimental data demonstrates that the present results are accurate. With the PECs determined here, the whole vibrational states for 11B2 (X3g-, A3u) and 10B11B (X3g-, A3u) are determined when the rotational quantum number J equals zero (J=0) by numerically solving the radical Schrdinger equation of nuclear motion. For each vibrational state of every isotope species, the vibrational level and inertial rotation constants are obtained, which are in excellent accordance with the experimental findings.

On basis set superposition error corrected stabilization energies for large n-body clusters

In this contribution, we propose an approximate basis set superposition error (BSSE) correction scheme for the site-site function counterpoise and for the Valiron-Mayer function counterpoise correction of second order to account for the basis set superposition error in clusters with a large number of subunits. The accuracy of the proposed scheme has been investigated for a water cluster series at the CCSD(T), CCSD, MP2, and self-consistent field levels of theory using Dunning's correlation consistent basis sets. The BSSE corrected stabilization energies for a series of water clusters are presented. A study regarding the possible savings with respect to computational resources has been carried out as well as a monitoring of the basis set dependence of the approximate BSSE corrections.

A systematical comparison of DFT methods in reproducing the interaction energies of halide series with protein moieties

A systematic theoretical investigation on the interaction energies of halogen-ionic bridges formed between halide ions and the polar H atoms bonded to N of protein moieties has been carried out by employing a variety of density functional methods. In this procedure, full geometry optimizations are performed at the Møller-Plesset second-order perturbation (MP2) level of theory in conjunction with the Dunning's augmented correlation-consistent basis set, aug-cc-pVDZ. Subsequently, two distinct basis sets, i.e. 6-311++G(df,pd) and aug-cc-pVTZ, are employed in the following single-point calculations so as to check the stability of the results obtained at the different levels of DFT. The performance of DFT methods has been evaluated by comparing the results with those obtained from the rigorous MP2 theory. It is shown that the B98, B97-1, and M05 give the lowest root-mean-square error (RMSE) for predicting fluoride-binding energies, M05-2X, MPW1B95, and MPW1PW91 have the best performance in reproducing chloride-binding energies, B97-1, PBEKCIS, and PBE1KCIS present the optimal result for bromide-binding energies, while B97-1, MPW1PW91, and TPSS perform most well on iodide-binding energies. The popular B3LYP functional seems to be quite modest for studying halide-protein moiety interactions. In addition, the PBE1KCIS functional provide accuracies close to the computationally expensive MP2 method for the calculation of interaction energies of all halide-binding systems.