Effective core potential

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.

Effective core potential. 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.

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. ... and previous relativistic core potential results. For the ...

The generalized relativistic effective core potential (GRECP) method is analyzed from theoretical and computational points of view. The Hamiltonian in the frozen-core approximation is compared with the Hamiltonian containing the GRECP operator. It is demonstrated that the GRECP operator can be derived from rather natural physical grounds and the procedure of the GRECP generation can be ...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. This is commonly accomplished by introducing effective core potentials (ECPs) or closely related pseudopotentials, that open opportunities to study systems with hundreds of valence electrons. ... the nonlocal integrals can be carried out explicitly saving thus the computational time while generating a different effective potential and ...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 ...Later on they applied the idea behind construction of Sadlej's polarized triple zeta basis set to double-zeta effective core potential basis sets and showed for the Raman intensities of the simple ...In our previous work we examined DFT using all-electron basis sets, but approaches incorporating effective core potentials (ECPs) are effective in reducing computational expense. With this in mind, our efforts were expanded to include evaluation of the performance of the basis set derived to approximate such an approach as well on the same set ...

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 ...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 …The analytical determination of second derivatives for ECP wavefunctions is the subject of the present paper. 2. Geaeral derivative formulas The form of the effective core potential used in this work at a given atom C is L ~ T ~ I11n> [U, (r) UL (r)]<ltn~ (1) 1=0 m - l where L 1 is the largest angular momentum quantum number appearing in the ...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, …This is commonly accomplished by introducing effective core potentials (ECPs) or closely related pseudopotentials, that open opportunities to study systems with hundreds of valence electrons. ... the nonlocal integrals can be carried out explicitly saving thus the computational time while generating a different effective potential and ...

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. 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 ... May 3, 2023 · "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 ... 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 ... 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

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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 …Jan 1, 1994 · 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. Both of these problems stem from the presence of large numbers of core electrons and, given that such electrons do not play a significant direct role in chemical behavior, it is natural to ask whether it is possible to model their effects in some simpler way. Such enquiries led to the invention of Effective Core Potentials (ECPs) or pseudopotentials.Good agreement between the calculated and experimental geometries was obtained. Although the size of the effective core potential (ECF) basis sets is about half or less than those of the non-ECP basis sets, 6-31G(p) and 6-311G(d,p), the obtained average errors and scale factors were comparable to those obtained using the non-ECP basis sets.A recently developed compact effective core potential (ECP) scheme for lanthanides [T. R. Cundari and W. J. Stevens, J. Chem. Phys. 98, 5555 (1993)] is applied to molecular species—the lanthanide trihalides (LnX3, Ln=Ce to Lu; X=F, Cl, Br, I). This research is the first ECP study of lanthanide trihalides in which 4f electrons are explicitly included in the lanthanide valence space. The high ...The relevant key words are, for example, B3LYP/Gen pseudo=cards. Also, the effective core potential and the related basis set need to be placed explicitly after the coordinates of atoms in the ...

The application of the frozen-core approximation (FCA) and effective core potentials (ECPs) within symmetry-adapted perturbation theory (SAPT) has been investigated and implemented. Unlike in the case of conventional electronic-structure theories, the development of a frozen-core version of SAPT is not straightforward.Numerically cheap single-core subsamplings have been used to build improved estimators for molecular properties in the variational Monte Carlo framework. The resulting estimators depend only on the valence electron positions and can be thought of as an exact effective core potential for the total energy. WeEffective core potentials represent the interactions of atomic nuclei and inner electrons with an equivalent potential energy, simplifying the solution of multi-electron systems while preserving the characteristics of the outer electrons. By employing effective core potentials, we can enhance the precision and efficiency of the neuralThe pseudopotential is an effective potential constructed to replace the atomic all-electron potential (full-potential) such that core states are eliminated and the valence electrons …Effective core potentials represent the interactions of atomic nuclei and inner electrons with an equivalent potential energy, simplifying the solution of multi-electron systems while preserving the characteristics of the outer electrons. By employing effective core potentials, we can enhance the precision and efficiency of the neural ORCA can use effective core potentials (also called pseudopotentials) that can be useful for efficient calculations on molecules containing heavy elements as the chemically irrelevant core electrons are not explicitly part of the electronic problem and are replaced by a core potential function instead. Note, however, that ECPs are not the most ... 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 ]. …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. Au 0 SDD. ECP bases are useful for two main reasons: reducing computational cost on systems with many metal centers, e.g. metal or metal oxide clusters or slabs. circumventing having to describe relativistic effects in deep core electrons. In metal complexes with only a few metal centers, using ECPs gives a very negligible speedup. Later on they applied the idea behind construction of Sadlej's polarized triple zeta basis set to double-zeta effective core potential basis sets and showed for the Raman intensities of the simple ...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 …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 ...

Fermionic neural network with effective cor e potential. Xiang Li ,1,*Cunwei Fan ,2,†Weiluo Ren,1and Ji Chen 3, 1 ByteDance Inc., Zhonghang Plaza, No. 43, North 3rd Ring West Road, Haidian ...

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 …This effective core potential includes a relativistic correction and should be used in combination with an own basis set. The other two pseudopotentials, namely that of Trail and Needs (TN) [11] and of Ovcharenko et al. (OAL) [10] lead to larger deviations which sometimes are bigger than 1 ...Effective Core Potential methods are classified in two families, according to their basic grounds. On the one hand, the Pseudopotential methods (PP) rely on an orbital transformation called the pseudoorbital transformation and they are ultimately related to the Phillips-Kleinman equation [2]. On the other hand, the Model Potential methods (MP ... # # Author: Qiming Sun <[email protected]> # ''' Effective core potential (ECP) This module exposes some ecp integration functions from the C implementation. Reference for ecp integral computation * Analytical integration J. Chem. Phys. 65, 3826 J. Chem. Phys. 111, 8778 J. Comput. Phys. 44, 289 * Numerical integration J. Comput. 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 ... 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 ...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.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 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 …

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The effective core potential (ECP) approximation has been vital in electronic structure calculations for several decades. An ECP is used to replace an atom's core (nucleus and tightly bound electrons) and is constructed to mimic the original core's effects on the valence electrons. This approximation provides important benefits such as the ...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.A fully relativistic effective core potential method has been developed for use in the valence‐only Dirac-Fock self‐consistent‐field calculations for atoms and molecules. The effective potentials are constructed so that the atomic valence‐only Dirac-Fock calculations reproduce the energies and the outer region of the corresponding ...8 Basis Sets and Effective Core Potentials 8.10 Introduction to Effective Core Potentials (ECPs) 8.12 Built-In ECPs. 8.11 ECP Fitting. The ECP matrix elements are arguably the most difficult one-electron integrals in existence. Indeed, using current methods, the time taken to compute the ECP integrals can exceed the time taken to compute the ...This Letter proposes an accurate scheme using frozen core orbitals, called the frozen core potential (FCP) method, to theoretically connect model potential calculations to all-electron (AE) ones. The present scheme is based on the Huzinaga-Cantu equation combined with spin-free relativistic Douglas-Kroll-Hess Hamiltonians.8 Basis Sets and Effective Core Potentials 8.10 Introduction to Effective Core Potentials (ECPs) 8.12 Built-In ECPs. 8.11 ECP Fitting. The ECP matrix elements are arguably the most difficult one-electron integrals in existence. Indeed, using current methods, the time taken to compute the ECP integrals can exceed the time taken to compute the ...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 ... 2. RELATIVISTIC EFFECTIVE CORE POTENTIALS Within the relativistic effective core potential approxi-mation, the effective Hamiltonian for an atom is usually written in the form Heff = () 1 v v v v v v v p q p p q p p r > ∑ ∑ h U+ + . ... (1) The summation in Eq. (1) runs over a subset of electrons, which are treated explicitly and marked by theIn order to study larger systems while retaining sufficient 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 semi-local potential terms in Hamiltonian.The performance of popular Hartree-Fock-based effective core potentials in Hartree-Fock and density functional calculations of 3d transition metals has been evaluated by basis-set convergence studies for ten cases: the equilibrium bond dissociation energy (De) for dissociation of ground-state Ti2 to ground and excited atoms, the ground-state …The greatest computational savings are achieved when the two-component relativistic effective core potential (RECP) approximation suggested originally by Lee et al. [56] is used (e.g., see reviews ...Routines for calculation of analytical second derivatives for the effective core potential have been developed. The present version allows for spdf basis sets with spdfg projection operators for HF, DFT, and MP2 methods and has been incorporated into the Gaussian package. Analytical frequency analysis has been applied to the characterization of a critical structure of Cp2Ru2(μ-H)4 and to the ... ….

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. It is removedOur method involves a hybrid of the Stuttgart semiempirical effective core potential and the compact effective potential (CEP) potential, and it uses a newly optimized polarized valence triple-ζ basis set. The combination of the new ECP and the new polarized valence triple-ζ basis set for Al is called the Minnesota effective core (MEC) method ...The application of the frozen-core approximation (FCA) and effective core potentials (ECPs) within symmetry-adapted perturbation theory (SAPT) has been investigated and implemented. Unlike in the case of conventional electronic-structure theories, the development of a frozen-core version of SAPT is not straightforward.The application of the frozen-core approximation (FCA) and effective core potentials (ECPs) within symmetry-adapted perturbation theory (SAPT) has been investigated and implemented. Unlike in the case of conventional electronic-structure theories, the development of a frozen-core version of SAPT is not straightforward. Au 0 SDD. ECP bases are useful for two main reasons: reducing computational cost on systems with many metal centers, e.g. metal or metal oxide clusters or slabs. circumventing having to describe relativistic effects in deep core electrons. In metal complexes with only a few metal centers, using ECPs gives a very negligible speedup. Fermionic Neural Network with Effective Core Potential Xiang Li ByteDance Inc, Zhonghang Plaza, No. 43, North 3rd Ring West Road, Haidian District, Beijing. {lixiang.62770689, renweiluo}@bytedance.com Cunwei Fan Department of Physics and Institute for Condensed Matter Theory, University of Illinois 1110 W. Green Street, Urbana, IL 61801, U.S.A ...We would like to show you a description here but the site won't allow us.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 ...Request PDF | On Jan 1, 2000, M. Dolg published Effective core potential | Find, read and cite all the research you need on ResearchGateWe 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 ... Effective core potential, We suggest 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. These bases are more suitable for density functional theory investigations than the previous 'double-ζ' contractions based upon Hartree-Fock atomic results. The original Hay ..., It is well known that quantum-chemical calculations based on the Schrödinger equation give poor results for compounds containing heavy elements because the Schrödinger equation is nonrelativistic. 1 One of the most widely applied methods to include relativity in electronic structure methods is the use of relativistic effective core potentials …, 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., 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 reduced computational timings., Physical Review Link Manager , Effective core potentials have been generated for Ti and Ni using atomic density functional theory (DFT) wave functions within the local density approximation. We find that these effective potentials give good agreement between all-electron and valence-electron calculations in TiF{sub 4} and Ni(CO){sub 4} for both the local-density (S-VWN) …, The calculations used correlationconsistent effective core potentials and corresponding VDZ basis sets for both H and C atoms from pseudopotentiallibrary.org. 74, 75 Each calculation was carried ..., Effective core potential methods for the lanthanides Thomas R. Cundari; Thomas R. Cundari Contribution from the Center for Advanced Research in Biotechnology, National Institutes of Standards and Technology, Rockville, Maryland 20850. Department of Chemistry, Memphis State University, Memphis, Tennessee 38152., The calculations used correlationconsistent effective core potentials and corresponding VDZ basis sets for both H and C atoms from pseudopotentiallibrary.org. 74, 75 Each calculation was carried ..., 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 …, Potential energy curves for the ground 1 Σ + g state of Xe 2, the first four states of the Xe + 2 ions, and the eight Xe* 2 excimer states corresponding to the addition of a 6sσ g Rydberg electron to these ion cores have been computed using averaged relativistic effective core potentials (AREP) and the self‐consistent field approximation for the …, EFFECTIVE CORE POTENTIALS MICHAEL DOLG Institut f ur Physikalische und Theoretische Chemie, Wegelerstr. 12, 53115 Bonn Germany E-mail: [email protected], The pseudopotential is an attempt to replace the complicated effects of the motion of the core (i.e. non-valence) electrons of an atom and its nucleus with an effective potential, or pseudopotential, so that the Schrödinger equation contains a modified effective potential term instead of the Coulombic potential term for core electrons normally ... , Both of these problems stem from the presence of large numbers of core electrons and, given that such electrons do not play a significant direct role in chemical behavior, it is natural to ask whether it is possible to model their effects in some simpler way. Such enquiries led to the invention of Effective Core Potentials (ECPs) or pseudopotentials., Ab initio effective core potentials (ECP's) have been generated to replace the innermost core electron for third‐row (K-Au), fourth‐row (Rb-Ag), and fifth‐row (Cs-Au) atoms. The outermost core orbitals—corresponding to the ns2np6 configuration for the three rows here—are not replaced by the ECP but are treated on an equal footing with the nd, (n+1)s and (n+1)p valence orbitals., Effective core potential integral and gradient evaluations are accelerated via implementation on graphical processing units (GPUs). Two simple formulas are proposed to estimate the upper bounds of ..., We would like to show you a description here but the site won’t allow us. , 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 ..., Effective Core Potential (ECP) Basis Sets . Svante Hedström, Batista Lab, Yale University . Tips and suggestions . If only one basis set (with ECP) is used for all atoms, it can be …, A consistent set of ab initio effective core potentials (ECP) has been generated for the main group elements from Na to Bi using the procedure originally developed by Kahn. The ECP’s are derived from all‐electron numerical Hartree–Fock atomic wave functions and fit to analytical representations for use in molecular calculations., By integrating effective core potentials with Ferminet, this work has achieved multiple excited state calculations with a precision comparable to experimental results, marking a significant advancement in practical applications and setting a new standard for theoretical excited state calculations. The essence of atomic structure …, Moreover, the DMC method can be further integrated with other powerful molecular neural networks 22,25, periodic neural network for solids 48, neural networks with effective core potential 49 ..., The ECP method dates back to 1960, when Phillips and Kleinman suggested an approximation scheme for discarding core orbitals in band calculations [1]. They replaced the full Fock-operator with the following operator: $$\hat F \to \hat F + \sum\limits_C {\left( {{ \in _v} - { \in _c}} \right)} \left| c \right. > < \left. c \right|$$ where ∈ v is a valence orbital energy and ∈ c are the core ..., Dec 16, 2020 · 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. , Sometimes 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 …, A new generation of effective core potentials: selected Lanthanides and heavy elements. We construct correlation-consistent effective core potentials (ccECPs) for a selected set of heavy atoms and f-elements that are of significant current interest in materials and chemical applications, including Y, Zr, Nb, Rh, Ta, Re, Pt, Gd, and Tb., You signed in with another tab or window. Reload to refresh your session. You signed out in another tab or window. Reload to refresh your session. You switched accounts on another tab or window. , The present section offers a brief introduction to the pseudopotential approach in general, followed by a review of the fundamentals of the effective core potentials and model core potentials, and starts from where the most recent review ended [].8.1.1 Separability of the Valence and Core Spaces. Mendeleev's Periodic Table of the chemical elements is one of the most important milestones in ..., Numerically cheap single-core subsamplings have been used to build improved estimators for molecular properties in the variational Monte Carlo framework. The resulting estimators depend only on the valence electron positions and can be thought of as an exact effective core potential for the total energy. We, 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 …, 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 reduced computational timings., 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 effective core potential operators of the functional form first proposed by Kahn et al. 4, 5 are widely used today. The only effort in using them in a molecular calculation rests in the evaluation of their one-electron integrals which are their matrix elements with the Cartesian Gaussian functions of the basis set.