Effective core potential

The molecular structure of Th@Au 6 was optimized at the DFT level using the BP86 27, 28 functional and the MWB SDD effective core potential together with the def2-TZVPP valence basis set for Au 29 and the def-TZVP 30 valence basis set for Th.

Jun 16, 2016 · The SDD effective core potential basis set is not suitable for the bond length calculation for PBDEs. The results of the two methods are close to the experimental data, while the all-electron basis set is more suitable for the bond length calculation for PBDEs than the SDD effective core potential basis set. Dec 23, 2023 · Calculate electronic excited states using neural networks with effective core potential. The essence of atomic structure theory, quantum chemistry, and computational materials science is solving the multi-electron stationary Schrödinger equation. The Quantum Monte Carlo-based neural network wave function method has surpassed traditional post ... Effective core potentials are analyzed from the standpoint of the underlying frozen core approximation. The content of the pseudoorbital, the content of the potential, and the properties of both are elaborated, showing the points at which they differ from the frozen core approximation and where possible deficiencies might lie.Even today, in spite of the development of fast computers and new efficient methods, the complexity of molecular calculations is rapidly increasing with the number of electrons. Quantum mechanical calculations on molecules containing first- and second-row atoms are now a routine task. The third-row atoms are certainly more complicated, owing to their larger size and more complicated d-orbitals ...The effective potentials mimic the action of the core on valence states and allow for valence-only calculations with resulting gains in efficiency. On a quantitative …Effective core potential is a type of numerical model of chemical elements so that their inner shell electrons not participate in numerical simulation. Instead, those electrons are combined with the atom core and treated as a collective potential to the remaining valence electrons. When constructedAn effective core potential system has been developed for heavy atoms in which relativistic effects are included in the effective potentials (EP). The EP's are based on numerical Dirac--Hartree--Fock calculations for atoms and on the Phillips--Kleinman transformation with other aspects similar to the treatments of Goddard and Melius and Kahn ...

Especially the SDB-cc-pVQZ basis set in conjunction with a core polarization potential (CPP) yields excellent agreement with experiment for compounds of the later heavy p-block elements. For accurate calculations on Ga (and, to a lesser extent, Ge) compounds, explicit treatment of 13 valence electrons appears to be desirable, while it seems ...2018-10-15 Update 2nd row He-core ccECPs to be consistent with JCP (2018) potentials. 2018-05-21 Added ccECPs for 2nd and 3rd row from Abdulgani Annaberdiyev (2018) and Chandler Bennett (2018). 2018-04-12 Added Trail-Needs CEPP (2015) and eCEPP (2017) potentials, basis sets, and orbitals. 2018-02-22 Add RRKJ and TM potentials for 3d …"Effective core potentials" are pseudopotentials that are used to treat the effects of core electrons; Pseudopotentials are a type of "effective potential", but effective potentials don't have to be pseudo (e.g. if we're just adding five non-psuedo potentials together to give us one combined "effective" potential). PySCF has different ...The basic assumptions of quantum chemical ab initio valence-only (VO) schemes, i.e., pseudopotential and modelpotential approaches, are briefly discussed. Both effective core potential schemes lead to a reduction of the computational effort for wavefunction-based as well as density functional theory electronic structure calculations in comparison to corresponding all-electron treatments and ...Abstract: The ab initio model potential method and its applications to atoms, molecules, and solids are reviewed here stressing its main characteristic of enabling a common computational strategy for effective core potential calculations in molecules and embedded cluster calculations of defects in solids and surface chemistry. As an effective core potential method it is shown to be very close ...In this paper we study the effective interactions of these systems by investigating the suitability of the Gauss-core model, to reproduce the relevant thermodynamic properties. ... Baeurle, S.A., Kroener, J. Modeling Effective Interactions of Micellar Aggregates of Ionic Surfactants with the Gauss-Core Potential. Journal of Mathematical ...

Potential energy curves for the ground 1Σ+g state of Xe2, the first four states of the Xe+2 ions, and the eight Xe*2 excimer states corresponding to the addition of a 6sσg Rydberg electron to these ion cores have been computed using averaged relativistic effective core potentials (AREP) and the self‐consistent field approximation for the valence electrons. The calculations were carried out ...New Effective Core Method (Effective Core Potential and Valence Basis Set) for Al Clusters and Nanoparticles and Heteronuclear Al-Containing Molecules. …Apr 1, 1993 · In this paper a complete set of effective core potentials (ECPs) and valence basis sets for the lanthanides (Ce to Lu) are derived. These ECPs are consistent not only within the lanthanide series, but also with the third‐row transition metals which bracket them. We propose large-core correlation-consistent pseudopotential basis sets for the heavy p-block elements Ga-Kr and In-Xe. The basis sets are of cc-pVTZ and cc-pVQZ quality, and have been optimized ...Apr 19, 2004 · The TMSZ basis set is used for gold atoms and the CEP-31G basis set is used for C, N and H atoms [30, 31], in which the effect of the core electrons is represented by effective core potential (ECP ...

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A method is described for obtaining l‐dependent relativistic effective core potentials (ECPs) from Dirac–Fock self‐consistent field atomic wave functions. These potentials are designed for use in nonrelativistic (NR) valence electron Hartree–Fock calculations on atoms and molecules. The novel aspect of this approach involves the averaging of the separately …The metal's non-valence electrons were replaced by HayWadt effective core potential (ECP) [38] for further reduction of computational load. QM-MM interactions were dealt with in terms of ...Besides, for these heavier elements the relativistic effects become important. One way to solve both problems simultaneously is to fit an effective core potential (ECP) to describe the core electrons using relativistic calculations, reducing the computational problem by treating only the valence electrons explicitly [22, 25, 27]. Most ECP ...Effective core potential (ECP) integrals are amongst the most difficult one-electron integrals to calculate due to the projection operators. The radial part of these operators may include r⁰, r ...For molecules containing the fourth-period element arsenic, we test (i, ii) the accuracy of all-electron (AE) basis sets from the def2-xZVP and ma-xZVP series (where xZ is S, TZ, or QZ), (iii) the accuracy of the 6-311G series of AE basis sets with additional polarization and diffuse functions, and (iv) the performance of effective core potentials (ECPs).A new generation of effective core potentials: selected lanthanides and heavy elements Haihan Zhou11, ∗and Benjamin Kincaid 1, Guangming Wang , Abdulgani Annaberdiyev 2, Panchapakesan Ganesh , and Lubos Mitas11 11) Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202, USA 2) Center for Nanophase …

Effective core potential (ECP) integrals are amongst the most difficult one-electron integrals to calculate due to the projection operators. The radial part of these operators may include r⁰, r ...Chapter 9. Effective Core Potentials. 9.1 Introduction. 9.2 ECP Fitting. 9.3 Built-In ECPs. 9.4 User-Defined ECPs. 9.5 ECPs and Electron Correlation. 9.6 Forces and Vibrational Frequencies with ECPs. 9.7 A Brief Guide to Q-Chem’s Built-In ECPs.8.10 Introduction to Effective Core Potentials (ECPs) 8.11 ECP Fitting; 8.12 Built-In ECPs. 8.12.0.1 Combining ECPs; 8.12.0.2 Examples; 8.13 User-Defined ECPs; ... Defines the effective core potential and associated basis set to be used TYPE: STRING DEFAULT: No ECP OPTIONS: General, Gen User ...Semantic Scholar extracted view of "Relativistic Effective Core Potentials" by M. Dolg. Semantic Scholar extracted view of "Relativistic Effective Core Potentials" by M. Dolg. Skip to search form Skip to main content Skip to account menu. Semantic Scholar's Logo. Search 214,771,107 papers from all fields of science ...Effective core potentials, Potential energy surfaces, Molecular geometry, Atomic and molecular spectra, Atomic properties, Oxides, Chemical elements, Chemical compounds, Many body problems, Density-matrix. I. INTRODUCTION. In recent decades, many-body electronic structure methods have enjoyed steady progression in accuracy and efficiency; this ...9 Effective Core Potentials. 9.1 Introduction; 9.2 ECP Fitting; 9.3 Built-In ECPs. 9.3.0.1 Combining ECPs; 9.3.0.2 Examples; 9.4 User-Defined ECPs; 9.5 ECPs and Electron Correlation; 9.6 Forces and Vibrational Frequencies with ECPs; 9.7 A Brief Guide to Q-Chem 's Built-In ECPs; 10 Exploring Potential Energy Surfaces: Critical Points and ...The present manuscript discusses the two branches of e ective core potential (ECP) approaches, i.e., the model potential (MP) and the pseudopotential (PP) tech-niques. The main focus is on those ECP schemes which proved to be successful in atomic and molecular relativistic electronic structure calculations during the pastSometimes this question also implies the explicit declaration of an external pseudopotential or Effective Core Potential (ECP). New basis sets and ECPs are published continuously in specialized journals all the time. The same happens with functionals for DFT calculations. The format in which they are published is free and …Abstract. In calculations of heavy-atom molecules with the shape-consistent Relativistic Effective Core Potential (RECP), only valence and some outer-core shells are treated explicitly, the shapes ...An effective core potential system has been developed for heavy atoms in which relativistic effects are included in the effective potentials (EP). The EP's are based on numerical Dirac-Hartree-Fock … Expand. 204. Save. Relativistic effects in ab initio effective core potentials for molecular calculations. Applications to the uranium atomEffective core potential basis sets. Hans Hellmann introduced pseudopotential or effective core potential in 1934, which is an approximation used to treat complex systems with simple description [76]. Pseudopotential explicitly treats only the chemically active valence electrons while the core electrons are 'frozen', being considered ...

1. Introduction. Effective core potential (ECP) approaches are almost as old as quantum mechanics [ 1, 2 ], but it was only during the last three decades that they became one of the mostly used approximate methods in both relativistic wavefunction-based ab initio quantum chemistry as well as corresponding density functional theory (DFT) schemes.

An ab initio configuration interaction (CI) study including the spin-orbit interaction is carried out for numerous valence and Rydberg states of the AsH radical by employing a relativistic effective core potential for the arsenic atom.Effective core potential (ECP) method was used to achieve reliable results for uranium. In this approach, inner-shell electrons are eliminated from the calculation and their effects on valence electrons are replaced with ECPs parameterized to fit observed atomic properties.Effective core potential (ECP) integrals are among the most difficult one-electron integrals to calculate due to the projection operators. The radial part of these operators may include r 0, r-1, and r-2 terms. For the r 0 terms, we exploit a simple analytic expression for the fundamental projected integral to derive new recurrence relations and upper bounds for ECP integrals.A new contraction of the basis sets associated with the Hay-Wadt relativistic effective core potentials (RECPs) for the main group and transition metal atoms are suggested, more suitable for density functional theory investigations than the previous 'double-ζ' contractions based upon Hartree-Fock atomic results. We suggest a new contraction of the basis sets associated with the Hay-Wadt ...Jan 1, 2010 · Abstract. A brief overview over the foundations and modern variants of the relativistic effective core potential method, i.e., energy-consistent and shape-consistent ab initio pseudopotentials as well as ab initio model potentials, is given. The energy-consistent ab initio pseudopotential approach is discussed in more detail, focussing on the ... Effective core potential (ECP) integrals are amongst the most difficult one-electron integrals to calculate due to the projection operators. The radial part of these operators may include r⁰, r ...Even today, in spite of the development of fast computers and new efficient methods, the complexity of molecular calculations is rapidly increasing with the number of electrons. Quantum mechanical calculations on molecules containing first- and second-row atoms are now a routine task. The third-row atoms are certainly more complicated, owing to ...The URL has moved hereThe pseudopotential must be used with a compatible basis set. Gaussian supports a new effective core potential (ECP) input format (similar to that used by ExtraBasis) which is described in the Format tab. Without any options, this keyword defaults to Pseudo=Read. However, the Cards option is by far its most-used mode.

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Apr 1, 1993 · In this paper a complete set of effective core potentials (ECPs) and valence basis sets for the lanthanides (Ce to Lu) are derived. These ECPs are consistent not only within the lanthanide series, but also with the third‐row transition metals which bracket them. The effective potential (also known as effective potential energy) combines multiple, perhaps opposing, effects into a single potential.In its basic form, it is the sum of the 'opposing' centrifugal potential energy with the potential energy of a dynamical system.It may be used to determine the orbits of planets (both Newtonian and relativistic) and to perform semi-classical atomic ...Jan 11, 2021 · For the transition metals atoms (Au), we used the [SD (60, MDF)] scheme to describe the effective core potential (ECP) 50,51. Accordingly, the normal optimization convergence criteria have been ... In this paper a complete set of effective core potentials (ECPs) and valence basis sets for the lanthanides (Ce to Lu) are derived. These ECPs are consistent not only within the lanthanide series, but also with the third‐row transition metals which bracket them. A 46‐electron core was chosen to provide the best compromise between computational …In order to calibrate the functionals and effective core potential/basis sets, we have decided to evaluate the geometry of the Fc 0 /Fc + RC system. Table S1 shows the optimized Fe-C, C-C, and C-H bond lengths using different XC functionals and pseudopotentials. All optimizations were further characterized by frequency calculations.On the other hand, the basis sets that using effective core potentials (ECP) have been being used widely to date for many types of molecules, due to their advantages [8, 20, 21]. Using ECP basis sets, helps to reduce the computational cost significantly, over the all electron basis sets, by replacing complete group of the inner electrons with a ...Jan 1, 2000 · Request PDF | On Jan 1, 2000, M. Dolg published Effective core potential | Find, read and cite all the research you need on ResearchGate The method is tantamount to computing an effective core potential on the fly, by efficiently subsampling the core regions with independent sidewalks. The removal of fluctuations in the core region enables also the dynamic in the valence region to be accelerated using a process with two time steps. As a function of the total number of … ….

Chapter 9. Effective Core Potentials. 9.1 Introduction. 9.2 ECP Fitting. 9.3 Built-In ECPs. 9.4 User-Defined ECPs. 9.5 ECPs and Electron Correlation. 9.6 Forces and Vibrational Frequencies with ECPs. 9.7 A Brief Guide to Q-Chem's Built-In ECPs.In the effective core potential (ECP) approximation, 24–27 a fraction of chemically inert core electrons is replaced by the pseudopotential constructed to reproduce atomic Hartree-Fock or Dirac-Hartree-Fock results. This approach has enabled quantum chemical calculations to be carried out on molecules containing heavy atoms with highly …Effective core potentials (ECPs) and closely related pseudopotentials provide a well-known technique for simplifying electronic structure calculations to valence-only degrees of freedom. The ECP Hamiltonians replace the core states by potentials with projectors that mimic the action of the core on the valence electrons with different symmetries.In the effective core potential (ECP) approximation, 24–27 a fraction of chemically inert core electrons is replaced by the pseudopotential constructed to reproduce atomic Hartree-Fock or Dirac-Hartree-Fock results. This approach has enabled quantum chemical calculations to be carried out on molecules containing heavy atoms with highly …Jul 15, 1979 · A method is described for obtaining l‐dependent relativistic effective core potentials (ECP s) from Dirac–Fock self‐consistent field atomic wave functions.These potentials are designed for use in nonrelativistic (NR) valence electron Hartree–Fock calculations on atoms and molecules. Effective core potentials. Pseudopotentials (effective core potentials, ECPs) may be defined at the beginning of BASIS blocks. The general form of the input cards is. which defines a pseudopotential for an atom specified either by a chemical symbol or a group number. The ECP specification may consist either of a single keyword, which references ... ADZP electric property calculations showed to be as fast as those that use augmented effective core potential basis sets. Introduction. Polarizability is a measure of the deformability of the electron density around an atomic or molecular system. It is a key element for describing electronic structure and plays an important role in governing ...This effective core potential treats cobalt as thought it were a one-electron atom, and, represents the potential from the 3d electrons (as well as the other core electrons) with a spherical effective core potential. The ECP method we employ yields valence orbitals with the correct nodal structure. In our cobalt hydride calculations the ...1. Introduction. Relativistic effective core potential (RECP) methods, also called relativistic pseudopotential (PP) methods, are probably the most successful approximate methods for the various properties of molecules containing heavy atoms, since RECP calculations economically yield results that are very close to the all-electron results without introducing any empirical parameters [1, 2, 3, 4]. Effective core potential, The nickel, palladium, and platinum atoms and their monohydrides are investigated using effective core potentials (ECP’s) recently introduced by Hay and Wadt [J. Chem. Phys. 82, 270, 299 (1985)]. The palladium and platinum ECP’s include relativistic effects. Two types of ECP’s, which differ in their definition of the core region, are used in conjunction with …, Feb 9, 2022 · We introduce new correlation consistent effective core potentials (ccECPs) for the elements I, Te, Bi, Ag, Au, Pd, Ir, Mo, and W with $4d$, $5d$, $6s$ and $6p$ valence spaces. These ccECPs are given as a sum of spin-orbit averaged relativistic effective potential (AREP) and effective spin-orbit (SO) terms. The construction involves several steps with increasing refinements from more simple to ... , The pseudopotential must be used with a compatible basis set. Gaussian supports a new effective core potential (ECP) input format (similar to that used by ExtraBasis) which is described in the Format tab. Without any options, this keyword defaults to Pseudo=Read. However, the Cards option is by far its most-used mode., An effective core potential is a basis function (a pseudo -orbital) that is used to “substitute” the inner (core) electrons of an atom. The pseudo-orbitals are formulated to be nodeless in the core region ( Figure 1 ). 4 It provides a relativistic effective potential for each core orbital eliminating the need for core basis functions and ... , The M08-SO was used with the basis set aug-cc-pVDZ-PP and an effective core potential (ECP) to determine the more stable structure of small gold clusters, Au n (2≤n ≤ 6). The averaged relativistic effective potential and spin-orbit operator for gold atoms are included in the effective core potential used . The populational analysis was …, The basic construction of ECPs involves reproducing valence one-particle eigenvalues and closely related one-particle orbital norm conservation, i.e., the amount of valence charge outside an appropriate effective ion radius. 11 Since the number of core states and their spatial properties vary, each angular momentum symmetry channel requires a different effective potential resulting in ..., Effective core potentials (ECPs) are widely used in electronic structure calculations of molecular and condensed systems. ... Clearly, more elaborate parameterizations are possible for finer accuracy targets. For instance, core-polarization effects and explicit spin-orbit coupling operators could be added subsequently, but that is …, We introduce new correlation consistent effective core potentials (ccECPs) for the elements I, Te, Bi, Ag, Au, Pd, Ir, Mo, and W with 4d, 5d, 6s, and 6p valence spaces. These ccECPs are given as a sum of spin-orbit averaged relativistic effective potential (AREP) and effective spin-orbit (SO) terms., Feb 9, 2022 · We introduce new correlation consistent effective core potentials (ccECPs) for the elements I, Te, Bi, Ag, Au, Pd, Ir, Mo, and W with $4d$, $5d$, $6s$ and $6p$ valence spaces. These ccECPs are given as a sum of spin-orbit averaged relativistic effective potential (AREP) and effective spin-orbit (SO) terms. The construction involves several steps with increasing refinements from more simple to ... , Institute for Theoretical Chemistry. Energy-consistent Pseudopotentials of the Stuttgart/Cologne Group. Chose the data format and click an element in the periodic table to get the pseudopotential parameters and corresponding optimized valence basis sets ! Data format: Molpro Gaussian Turbomole Crystal06 and earlier versions Crystal09., An effective core potential system has been developed for heavy atoms in which relativistic effects are included in the effective potentials (EP). The EP's are based on numerical Dirac-Hartree-Fock calculations for atoms and on the Phillips-Kleinman transformation with other aspects similar to the treatments of Goddard and Melius and ..., The effective core potential (ECP) approach is one of the oldest and still one of the most frequently used methods in relativistic quantum chemistry [1, 2]. Following chemical intuition, an atom is partitioned into a core and a valence electron system. The chemically inert core of the atom is considered to be frozen., Barasiey's effective core potential [37] and by using a good quality basis set- As we have recently discussed in detail [381, this - originally atomic potential leads to an unbalanced treatment of core polarzation effects in molecules since it lacks electron-other core polarization contributions. Indeed. the OcuIations apparently exaggerate the ..., The two effective core potential schemes investigated are those of Hay and Wadt [33] (termed LANL2DZ in G aussian) and Stevens et al. [34] (CEP-31G in G aussian). In all cases, the valence basis sets of main group elements were augmented with a d-polarization function chosen from the 6-31G∗ or 6-311G∗ basis sets., Especially the SDB-cc-pVQZ basis set in conjunction with a core polarization potential (CPP) yields excellent agreement with experiment for compounds of the later heavy p-block elements. For accurate calculations on Ga (and, to a lesser extent, Ge) compounds, explicit treatment of 13 valence electrons appears to be desirable, while it seems ..., Comments on "Effective Core Potentials" [M.Dolg, Modern Methods and Algorithms of Quantum Chemistry (Ed. by J.Grotendorst, John von Neumann Institute for Computing, J\"ulich, NIC Series, Vol.1 ..., The problem is that an ECP is designed to produce the effective potential of core electrons, and an all-electron basis set will include basis functions meant to model the core electrons. At best, those core basis functions are poorly optimized for your problem. At worst, you will run into SCF convergence problems., Results of extensive all-electron and effective core potential (ECP) ab initio calculations on the ground state properties of ArH +, KrH + and XeH + are reported. It is demonstrated that, for the equilibrium distance and harmonic frequency, the ECPs combined with a hydrogen basis set of sufficient size and flexibility lead to an accuracy quite similar …, The Hellmann-Feynman force method is combined with the effective-core potential (ECP) method. Based on a theorem previously reported, we have added derivative AOsr' to the original basis r, and confirmed that the wavefunctions of the ECP method essentially satisfy the Hellmann-Feynman (HF) theorem.This makes it easier to apply an intuitive force concept quantitatively to molecular systems ..., The ground state geometries of small anionic Ag−n(n=2–9) clusters were determined in the framework of the Hartree–Fock procedure employing a relativistic effective core potential (RECP) accounting for core–valence correlation (CVC) effects. Large scale configuration interaction (CI) calculations for 5s electrons only were carried out in order to determine …, tive core potentials (ECP) have been being used widely to date for many types of molecules, due to their advantages [8, 20, 21]. Using ECP basis sets, helps to reduce the computational cost significantly, over the all electron basis sets, by replacing complete group of the inner electrons with a representative effective core potential [1, 22, 23]., We introduce new correlation consistent effective core potentials (ccECPs) for the elements I, Te, Bi, Ag, Au, Pd, Ir, Mo, and W with $4d$, $5d$, $6s$ and $6p$ valence spaces. These ccECPs are given as a sum of spin-orbit averaged relativistic effective potential (AREP) and effective spin-orbit (SO) terms. The construction involves several steps with increasing refinements from more simple to ..., 有效芯势（Effective Core Potential, ECP）包括赝势（Pseudopotential, PP）和模型芯势（Model Core Potential, MCP）。 量子化学计算中的PP与平面波计算中的PP并无本质差别，只不过表示为简明的解析式形式。 包括BDF在内的大部分量子化学软件都支持PP，而支持MCP的量子化学软件 ..., Relativistic Effective Core Potential Method 2. The Effective Core Potential Method III 2.1. General Theory As mentioned above, the procedure is based on the conception that the chemical effects are essentially determined by the valence electrons only, the core electrons shielding the nucleus. Accordingly, the one basic, accuracy, we integrate a powerful neural-network-based model (FermiNet) with the effective core potential method, which helps to reduce the complexity of the problem by replacing inner core electrons with additional semilocal potential terms in the Hamiltonian. In this work, we calculate the ground-state energy of 3d transition, Effective core potential methods for the lanthanides. Thomas R. Cundari; Walter J. Stevens. J. Chem. Phys. 98, 5555–5565 (1993) …, Even today, in spite of the development of fast computers and new efficient methods, the complexity of molecular calculations is rapidly increasing with the number of electrons. Quantum mechanical calculations on molecules containing first- and second-row atoms are now a routine task. The third-row atoms are certainly more complicated, owing to their larger size and more complicated d-orbitals ..., Effective core potentials derived from these revised pseudo‐orbitals were used to compute potential energy curves for the ground states of F2, Cl2, and LiCl and the results are compared with previous all‐electron and effective potential calculations., Using effective core potentials to account for inner electrons enhances the precision of vertical excitation and ionization energies. This approach has proved effective in computing ground state energies for elements like Lithium to Gallium and in calculating energy levels and wave functions for atoms and molecules with second and fourth period ..., For the Cl atom, we use an AREP type, correlation consistent effective core potential (ccECP) with 7 valence electrons [35]. The high accuracy of this ECP was demonstrated in the original paper ..., This effective core potential treats cobalt as thought it were a one-electron atom, and, represents the potential from the 3d electrons (as well as the other core electrons) with a spherical effective core potential. The ECP method we employ yields valence orbitals with the correct nodal structure. In our cobalt hydride calculations the ..., The problem is that an ECP is designed to produce the effective potential of core electrons, and an all-electron basis set will include basis functions meant to model the core electrons. At best, those core basis functions are poorly optimized for your problem. At worst, you will run into SCF convergence problems., Computational studies using DFT and an effective core potential appropriate for platinum were conducted on these Pt+(acetylene) n complexes to determine their structures and to predict IR spectra corresponding to each structural isomer identified.These results are summarized in Table 1, and the