Understanding molecular interactions in mechanically interlocked molecules (MIMs) is challenging ... more Understanding molecular interactions in mechanically interlocked molecules (MIMs) is challenging because they can be either donor–acceptor interactions or radical pairing interactions, depending on the charge states and multiplicities in the different components of the MIMs. In this work, for the first time, the interactions between cyclobis(paraquat-p-phenylene) (abbreviated as CBPQTn+ (n = 0–4)) and a series of recognition units (RUs) were investigated using the energy decomposition analysis approach (EDA). These RUs include bipyridinium radical cation (BIPY•+), naphthalene-1,8:4,5-bis(dicarboximide) radical anion (NDI•−), their oxidized states (BIPY2+ and NDI), neutral electron-rich tetrathiafulvalene (TTF) and neutral bis-dithiazolyl radical (BTA•). The results of generalized Kohn–Sham energy decomposition analysis (GKS-EDA) reveal that for the CBPQTn+···RU interactions, correlation/dispersion terms always have large contributions, while electrostatic and desolvation terms are s...
In this paper, the nature of electron-pair bonds is explored from an energy decomposition perspec... more In this paper, the nature of electron-pair bonds is explored from an energy decomposition perspective. The recently developed valence bond energy decomposition analysis (VB-EDA) scheme is extended for the classification of electron-pair bonds, which divides the bond dissociation energy into frozen, reference state switch, quasi-resonance and polarization terms. VB-EDA investigations are devoted to a series of electron-pair bonds, including the covalent bonds (H–H, H3C–CH3, H3C–H, and H2N–NH2), the ionic bonds (Na–Cl, Li–F), the charge-shift (CS) bonds (HO–OH, F–F, Cl–Cl, Br–Br, H–F, F–Cl, H3Si–F and H3Si–Cl), and the inverted central carbon–carbon bond in [1.1.1] propallene. It is shown that the VB-EDA approach at the VBSCF level is capable of predicting the characters of the electron-pair bonds. The perspective from VB-EDA illustrates that a relatively high value of quasi-resonance term indicates a CS bond while a large portion of polarization term suggests a classical covalent bond.
In this work, the analysis results of three energy decomposition analysis (EDA) methods, namely, ... more In this work, the analysis results of three energy decomposition analysis (EDA) methods, namely, generalized Kohn–Sham (GKS) EDA, extended transition state EDA, and density functional theory symmetry-adapted perturbation theory (DFT-SAPT), were extensively assessed for various intermolecular interactions. According to the physical meanings of their definitions, the EDA terms in the three methods can be grouped into four categories: electrostatics, exchange–repulsion/Pauli/exchange, polarization/orbital/induction, and CD (correlation/dispersion/dispersion) terms. Test examples include 1092 non-covalent interaction complexes in the standard sets (S66, PNICO23, HAL59, IL16, S66 × 8, and X40 × 10). It is concluded that despite the different basis sets and different running platforms (programs), the results of the three EDA methods are comparable. In general, except the dispersion term, all the EDA terms in the three methods are in excellent agreement. The CD term in GKS-EDA is comparabl...
: The accurate description of strongly correlated systems, also known as multireference systems, ... more : The accurate description of strongly correlated systems, also known as multireference systems, requires a balanced treatment of static and dynamic correlations and is an important target for developing quantum chemical methods. An appealing treatment to economically describe strongly correlated systems is the multireference density function theory (MRDFT) approach, in which the static correlation is included in the multiconfigurational wave function, while the density functional includes the dynamic correlation. This mini-review focuses on the recent progress and applications of the density functional methods based on valence bond theory. A series of density functional valence bond (DFVB) methods are surveyed, including the dynamic correlation correction- based and Hamiltonian matrix correction-based DFVB methods, the hybrid one-parameter DFVB methods, the block-localized density functional theory and the multistate density functional theory. These methods have been applied to various chemical and physical property calculations of strongly correlated systems, including resonance energies, potential energy curves, spectroscopic constants, atomization energies, spin state energy gaps, excitation energies, and reaction barriers. Most of the test results show that the density functional methods based on VB theory give comparable accuracy but require lower computational cost than high-level quantum computational methods and thus provide a promising strategy for studying strongly correlated systems.
A novel energy decomposition analysis scheme, named DFTB-EDA, is proposed based on the density fu... more A novel energy decomposition analysis scheme, named DFTB-EDA, is proposed based on the density functional based tight binding method (DFTB/TD-DFTB), which is a semi-empirical quantum mechanical method based on KS-DFT for large-scale calculations. In DFTB-EDA, the total interaction energy is divided into three terms: frozen density, polarization and dispersion. Owing to the small cost of DFTB/TD-DFTB, DFTB-EDA is capable of analyzing intermolecular interactions in large molecular systems containing several thousand atoms with high computational efficiency. It can be used not only for ground states but also for excited states. Test calculations, involving the S66 and L7 databases, several large molecules and non-covalent bonding complexes in their lowest excited states, demonstrate the efficiency, usefulness and capabilities of DFTB-EDA. Finally, the limits of DFTB-EDA are pointed out.
Xiamen valence bond (XMVB), which is an ab initio nonorthogonal valence bond program, has been pr... more Xiamen valence bond (XMVB), which is an ab initio nonorthogonal valence bond program, has been progressively developed and refined during the last 25 years. As the release of XMVB 1.0 in 2004, a number of significant enhancements and improvements have been made to the program. As a consequence, a new version, XMVB 2.0, has been released and will be described in this article. In XMVB 2.0, the nonorthogonal orbital-based reduced density matrix approach for the valence bond (VB) theory is implemented, based on the second quantization scheme for nonorthogonal orbitals. The present article also describes the recently developed algorithms for orbital optimization in the VB self-consist field (VBSCF) method, in which the internal contraction of wave function is used for computing energy gradients. Moreover, several newly implemented ab initio VB methods, such as VBSCF(CAS), internally contracted VB second-order perturbation theory (icVBPT2), VB polarizable continuum model, VB effective fragment potential (VBECP), and density-functional-based VB, are briefly reviewed in this article. Finally, test calculations of several planar arenes, in which up to 18 active electrons are involved, are performed with XMVB 2.0.
The journal of physical chemistry. A, May 13, 2016
Both proper, red-shifting and improper, blue-shifting hydrogen bonds have been well recognized wi... more Both proper, red-shifting and improper, blue-shifting hydrogen bonds have been well recognized with enormous experimental and computational studies. The current consensus is that there is no difference in nature between these two kinds of hydrogen bonds, where the electrostatic interaction dominates. Since most if not all the computational studies are based on molecular orbital (MO) theory, it would be interesting to gain insights into the hydrogen bonds with modern valence bond (VB) theory. In this work, we performed ab initio VBSCF study on a series of hydrogen bonding systems where the sole hydrogen bond donor CF3H interacts with ten hydrogen bond acceptors Y (=NH2CH3, NH3, NH2Cl, OH-, H2O, CH3OH, (CH3)2O, F-, HF or CH3F). This series includes four red-shifting and six blue-shifting hydrogen bonds. In consistent with existing findings in literatures, VB-based energy decomposition analyses show that electrostatic interaction plays the dominating role and polarization plays the sec...
You need to cite the references of XMVB as following formats when the calculations are proc-ceded... more You need to cite the references of XMVB as following formats when the calculations are proc-ceded with XMVB program. A) J. Chem. Phys. format: The ab initio Valence Bond calculations are performed with the XMVB program. The ab initio Valence Bond calculations are performed with the XMVB program. XMVB version 2.0 is a program that performs ab initio valence bond calculations. XMVB version 2.0 will be distributed from Xiamen University for free. The principal user will be asked to fill a license agreement and send the signed agreement to:
A fast and multipurpose energy decomposition analysis (EDA) program, called XEDA, is introduced f... more A fast and multipurpose energy decomposition analysis (EDA) program, called XEDA, is introduced for quantitative analysis of intermolecular interactions. This program contains a series of variational EDA methods, including LMO-EDA, GKS-EDA and their extensions, to analyze non-covalent interactions and strong chemical bonds in various environments. XEDA is highly efficient with a similar computational scaling of single point energy calculations. Its efficiency and universality are validated by a series of test examples including van der Waals interactions, hydrogen bonds, radical-radical interactions and strong covalent bonds.
Abstract We present a study of spectroscopic identification towards the molecular aggregates of Z... more Abstract We present a study of spectroscopic identification towards the molecular aggregates of Zinc tetraphenylporphyrin (ZnTPP) illustrating how the energy states and intermolecular interactions determine the tunable properties of functional materials in condensation processes. Distinguishable fingerprints of ZnTPP nanorods and nanosheets are addressed utilizing X-ray diffraction (XRD), Raman and UV–vis absorption spectroscopies. Although these ZnTPPs are assigned to J-aggregation at different extent, the spectral analysis reveals a significant role of the intermolecular interactions associated with varying mesoscale architectures. Energy decomposition analysis (EDA) revealed that the varied ZnTPP aggregates are stabilized by altered dispersion interactions due to the dominant π ··· π stacking between the monomers.
It is found by experiment that the cationic halogen bond donors (cationic iodoimidazolium compoun... more It is found by experiment that the cationic halogen bond donors (cationic iodoimidazolium compounds) can activate the Ritter-type solvolysis of benzhydryl bromide, while the cationic hydrogen bond donors (cationic imidazolium compounds) could not. To understand the activation mechanism, various noncovalent interactions between benzhydryl bromide and a series of activators in solution, including halogen bond, hydrogen bond, lone pair•••π/π + , and C−H•••π/π + , were explored theoretically. Our study revealed that the activation difference can be contributed by the variation of the noncovalent interactions. For halogen bond donors, the successful activation is attributed by halogen bond and lone pair•••π. The halogen bonds mainly provide the stabilization energy of the ion-pair complex with the help of lone pair•••π. For hydrogen-bond donors, the contribution of the hydrogen bond is unable to compensate the like-charge repulsion arising from the generation of the carbocation, leading to the unsuccessful activation. In general, lone pair•••π makes a difference.
A recently developed valence-bond-based multireference density functional theory, named λ-DFVB, i... more A recently developed valence-bond-based multireference density functional theory, named λ-DFVB, is revisited in this paper. λ-DFVB remedies the double-counting error of electron correlation by decomposing the electron–electron interactions into the wave function term and density functional term with a variable parameter λ. The λ value is defined as a function of the free valence index in our previous scheme, denoted as λ-DFVB(K) in this paper. Here we revisit the λ-DFVB method and present a new scheme based on natural orbital occupation numbers (NOONs) for parameter λ, named λ-DFVB(IS), to simplify the process of λ-DFVB calculation. In λ-DFVB(IS), the parameter λ is defined as a function of NOONs, which are straightforwardly determined from the many-electron wave function of the molecule. Furthermore, λ-DFVB(IS) does not involve further self-consistent field calculation after performing the valence bond self-consistent field (VBSCF) calculation, and thus, the computational effort in...
Understanding molecular interactions in mechanically interlocked molecules (MIMs) is challenging ... more Understanding molecular interactions in mechanically interlocked molecules (MIMs) is challenging because they can be either donor–acceptor interactions or radical pairing interactions, depending on the charge states and multiplicities in the different components of the MIMs. In this work, for the first time, the interactions between cyclobis(paraquat-p-phenylene) (abbreviated as CBPQTn+ (n = 0–4)) and a series of recognition units (RUs) were investigated using the energy decomposition analysis approach (EDA). These RUs include bipyridinium radical cation (BIPY•+), naphthalene-1,8:4,5-bis(dicarboximide) radical anion (NDI•−), their oxidized states (BIPY2+ and NDI), neutral electron-rich tetrathiafulvalene (TTF) and neutral bis-dithiazolyl radical (BTA•). The results of generalized Kohn–Sham energy decomposition analysis (GKS-EDA) reveal that for the CBPQTn+···RU interactions, correlation/dispersion terms always have large contributions, while electrostatic and desolvation terms are s...
In this paper, the nature of electron-pair bonds is explored from an energy decomposition perspec... more In this paper, the nature of electron-pair bonds is explored from an energy decomposition perspective. The recently developed valence bond energy decomposition analysis (VB-EDA) scheme is extended for the classification of electron-pair bonds, which divides the bond dissociation energy into frozen, reference state switch, quasi-resonance and polarization terms. VB-EDA investigations are devoted to a series of electron-pair bonds, including the covalent bonds (H–H, H3C–CH3, H3C–H, and H2N–NH2), the ionic bonds (Na–Cl, Li–F), the charge-shift (CS) bonds (HO–OH, F–F, Cl–Cl, Br–Br, H–F, F–Cl, H3Si–F and H3Si–Cl), and the inverted central carbon–carbon bond in [1.1.1] propallene. It is shown that the VB-EDA approach at the VBSCF level is capable of predicting the characters of the electron-pair bonds. The perspective from VB-EDA illustrates that a relatively high value of quasi-resonance term indicates a CS bond while a large portion of polarization term suggests a classical covalent bond.
In this work, the analysis results of three energy decomposition analysis (EDA) methods, namely, ... more In this work, the analysis results of three energy decomposition analysis (EDA) methods, namely, generalized Kohn–Sham (GKS) EDA, extended transition state EDA, and density functional theory symmetry-adapted perturbation theory (DFT-SAPT), were extensively assessed for various intermolecular interactions. According to the physical meanings of their definitions, the EDA terms in the three methods can be grouped into four categories: electrostatics, exchange–repulsion/Pauli/exchange, polarization/orbital/induction, and CD (correlation/dispersion/dispersion) terms. Test examples include 1092 non-covalent interaction complexes in the standard sets (S66, PNICO23, HAL59, IL16, S66 × 8, and X40 × 10). It is concluded that despite the different basis sets and different running platforms (programs), the results of the three EDA methods are comparable. In general, except the dispersion term, all the EDA terms in the three methods are in excellent agreement. The CD term in GKS-EDA is comparabl...
: The accurate description of strongly correlated systems, also known as multireference systems, ... more : The accurate description of strongly correlated systems, also known as multireference systems, requires a balanced treatment of static and dynamic correlations and is an important target for developing quantum chemical methods. An appealing treatment to economically describe strongly correlated systems is the multireference density function theory (MRDFT) approach, in which the static correlation is included in the multiconfigurational wave function, while the density functional includes the dynamic correlation. This mini-review focuses on the recent progress and applications of the density functional methods based on valence bond theory. A series of density functional valence bond (DFVB) methods are surveyed, including the dynamic correlation correction- based and Hamiltonian matrix correction-based DFVB methods, the hybrid one-parameter DFVB methods, the block-localized density functional theory and the multistate density functional theory. These methods have been applied to various chemical and physical property calculations of strongly correlated systems, including resonance energies, potential energy curves, spectroscopic constants, atomization energies, spin state energy gaps, excitation energies, and reaction barriers. Most of the test results show that the density functional methods based on VB theory give comparable accuracy but require lower computational cost than high-level quantum computational methods and thus provide a promising strategy for studying strongly correlated systems.
A novel energy decomposition analysis scheme, named DFTB-EDA, is proposed based on the density fu... more A novel energy decomposition analysis scheme, named DFTB-EDA, is proposed based on the density functional based tight binding method (DFTB/TD-DFTB), which is a semi-empirical quantum mechanical method based on KS-DFT for large-scale calculations. In DFTB-EDA, the total interaction energy is divided into three terms: frozen density, polarization and dispersion. Owing to the small cost of DFTB/TD-DFTB, DFTB-EDA is capable of analyzing intermolecular interactions in large molecular systems containing several thousand atoms with high computational efficiency. It can be used not only for ground states but also for excited states. Test calculations, involving the S66 and L7 databases, several large molecules and non-covalent bonding complexes in their lowest excited states, demonstrate the efficiency, usefulness and capabilities of DFTB-EDA. Finally, the limits of DFTB-EDA are pointed out.
Xiamen valence bond (XMVB), which is an ab initio nonorthogonal valence bond program, has been pr... more Xiamen valence bond (XMVB), which is an ab initio nonorthogonal valence bond program, has been progressively developed and refined during the last 25 years. As the release of XMVB 1.0 in 2004, a number of significant enhancements and improvements have been made to the program. As a consequence, a new version, XMVB 2.0, has been released and will be described in this article. In XMVB 2.0, the nonorthogonal orbital-based reduced density matrix approach for the valence bond (VB) theory is implemented, based on the second quantization scheme for nonorthogonal orbitals. The present article also describes the recently developed algorithms for orbital optimization in the VB self-consist field (VBSCF) method, in which the internal contraction of wave function is used for computing energy gradients. Moreover, several newly implemented ab initio VB methods, such as VBSCF(CAS), internally contracted VB second-order perturbation theory (icVBPT2), VB polarizable continuum model, VB effective fragment potential (VBECP), and density-functional-based VB, are briefly reviewed in this article. Finally, test calculations of several planar arenes, in which up to 18 active electrons are involved, are performed with XMVB 2.0.
The journal of physical chemistry. A, May 13, 2016
Both proper, red-shifting and improper, blue-shifting hydrogen bonds have been well recognized wi... more Both proper, red-shifting and improper, blue-shifting hydrogen bonds have been well recognized with enormous experimental and computational studies. The current consensus is that there is no difference in nature between these two kinds of hydrogen bonds, where the electrostatic interaction dominates. Since most if not all the computational studies are based on molecular orbital (MO) theory, it would be interesting to gain insights into the hydrogen bonds with modern valence bond (VB) theory. In this work, we performed ab initio VBSCF study on a series of hydrogen bonding systems where the sole hydrogen bond donor CF3H interacts with ten hydrogen bond acceptors Y (=NH2CH3, NH3, NH2Cl, OH-, H2O, CH3OH, (CH3)2O, F-, HF or CH3F). This series includes four red-shifting and six blue-shifting hydrogen bonds. In consistent with existing findings in literatures, VB-based energy decomposition analyses show that electrostatic interaction plays the dominating role and polarization plays the sec...
You need to cite the references of XMVB as following formats when the calculations are proc-ceded... more You need to cite the references of XMVB as following formats when the calculations are proc-ceded with XMVB program. A) J. Chem. Phys. format: The ab initio Valence Bond calculations are performed with the XMVB program. The ab initio Valence Bond calculations are performed with the XMVB program. XMVB version 2.0 is a program that performs ab initio valence bond calculations. XMVB version 2.0 will be distributed from Xiamen University for free. The principal user will be asked to fill a license agreement and send the signed agreement to:
A fast and multipurpose energy decomposition analysis (EDA) program, called XEDA, is introduced f... more A fast and multipurpose energy decomposition analysis (EDA) program, called XEDA, is introduced for quantitative analysis of intermolecular interactions. This program contains a series of variational EDA methods, including LMO-EDA, GKS-EDA and their extensions, to analyze non-covalent interactions and strong chemical bonds in various environments. XEDA is highly efficient with a similar computational scaling of single point energy calculations. Its efficiency and universality are validated by a series of test examples including van der Waals interactions, hydrogen bonds, radical-radical interactions and strong covalent bonds.
Abstract We present a study of spectroscopic identification towards the molecular aggregates of Z... more Abstract We present a study of spectroscopic identification towards the molecular aggregates of Zinc tetraphenylporphyrin (ZnTPP) illustrating how the energy states and intermolecular interactions determine the tunable properties of functional materials in condensation processes. Distinguishable fingerprints of ZnTPP nanorods and nanosheets are addressed utilizing X-ray diffraction (XRD), Raman and UV–vis absorption spectroscopies. Although these ZnTPPs are assigned to J-aggregation at different extent, the spectral analysis reveals a significant role of the intermolecular interactions associated with varying mesoscale architectures. Energy decomposition analysis (EDA) revealed that the varied ZnTPP aggregates are stabilized by altered dispersion interactions due to the dominant π ··· π stacking between the monomers.
It is found by experiment that the cationic halogen bond donors (cationic iodoimidazolium compoun... more It is found by experiment that the cationic halogen bond donors (cationic iodoimidazolium compounds) can activate the Ritter-type solvolysis of benzhydryl bromide, while the cationic hydrogen bond donors (cationic imidazolium compounds) could not. To understand the activation mechanism, various noncovalent interactions between benzhydryl bromide and a series of activators in solution, including halogen bond, hydrogen bond, lone pair•••π/π + , and C−H•••π/π + , were explored theoretically. Our study revealed that the activation difference can be contributed by the variation of the noncovalent interactions. For halogen bond donors, the successful activation is attributed by halogen bond and lone pair•••π. The halogen bonds mainly provide the stabilization energy of the ion-pair complex with the help of lone pair•••π. For hydrogen-bond donors, the contribution of the hydrogen bond is unable to compensate the like-charge repulsion arising from the generation of the carbocation, leading to the unsuccessful activation. In general, lone pair•••π makes a difference.
A recently developed valence-bond-based multireference density functional theory, named λ-DFVB, i... more A recently developed valence-bond-based multireference density functional theory, named λ-DFVB, is revisited in this paper. λ-DFVB remedies the double-counting error of electron correlation by decomposing the electron–electron interactions into the wave function term and density functional term with a variable parameter λ. The λ value is defined as a function of the free valence index in our previous scheme, denoted as λ-DFVB(K) in this paper. Here we revisit the λ-DFVB method and present a new scheme based on natural orbital occupation numbers (NOONs) for parameter λ, named λ-DFVB(IS), to simplify the process of λ-DFVB calculation. In λ-DFVB(IS), the parameter λ is defined as a function of NOONs, which are straightforwardly determined from the many-electron wave function of the molecule. Furthermore, λ-DFVB(IS) does not involve further self-consistent field calculation after performing the valence bond self-consistent field (VBSCF) calculation, and thus, the computational effort in...
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