Q-Chem 5.2 User’s Manual
Contents
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1 Introduction
- 1.1 About This Manual
- 1.2 Q-Chem, Inc.
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1.3 Q-Chem Features
- 1.3.1 New Features in Q-Chem 5.2
- 1.3.2 New Features in Q-Chem 5.1
- 1.3.3 New Features in Q-Chem 5.0
- 1.3.4 New Features in Q-Chem 4.4
- 1.3.5 New Features in Q-Chem 4.3
- 1.3.6 New Features in Q-Chem 4.2
- 1.3.7 New Features in Q-Chem 4.1
- 1.3.8 New Features in Q-Chem 4.0.1
- 1.3.9 New Features in Q-Chem 4.0
- 1.3.10 Summary of Features in Q-Chem versions 3.x
- 1.3.11 Summary of Features Prior to Q-Chem 3.0
- 1.4 Citing Q-Chem
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2 Installation, Customization, and Execution
- 2.1 Installation Requirements
- 2.2 Installing Q-Chem
- 2.3 Q-Chem Auxiliary files ($QCAUX)
- 2.4 Q-Chem Run-time Environment Variables
- 2.5 User Account Adjustments
- 2.6 Further Customization: .qchemrc and preferences Files
- 2.7 Running Q-Chem
- 2.8 Parallel Q-Chem Jobs
- 2.9 IQmol Installation Requirements
- 2.10 Testing and Exploring Q-Chem
- 3 Q-Chem Inputs
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4 Self-Consistent Field Ground-State Methods
- 4.1 Overview
- 4.2 Theoretical Background
- 4.3 Basic SCF Job Control
- 4.4 SCF Initial Guess
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4.5 Converging SCF Calculations
- 4.5.1 Introduction
- 4.5.2 Basic Convergence Control Options
- 4.5.3 Direct Inversion in the Iterative Subspace (DIIS)
- 4.5.4 Geometric Direct Minimization (GDM)
- 4.5.5 Direct Minimization (DM)
- 4.5.6 Maximum Overlap Method (MOM)
- 4.5.7 Relaxed Constraint Algorithm (RCA)
- 4.5.8 User-Customized Hybrid SCF Algorithm
- 4.5.9 Internal Stability Analysis and Automated Correction for Energy Minima
- 4.5.10 Small-Gap Systems
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4.6 Large Molecules and Linear Scaling Methods
- 4.6.1 Introduction
- 4.6.2 Continuous Fast Multipole Method (CFMM)
- 4.6.3 Linear Scaling Exchange (LinK) Matrix Evaluation
- 4.6.4 Incremental and Variable Thresh Fock Matrix Building
- 4.6.5 Fourier Transform Coulomb Method
- 4.6.6 Resolution of the Identity Fock Matrix Methods
- 4.6.7 PARI-K Fast Exchange Algorithm
- 4.6.8 CASE Approximation
- 4.6.9 occ-RI-K Exchange Algorithm
- 4.7 Dual-Basis Self-Consistent Field Calculations
- 4.8 Hartree-Fock and Density-Functional Perturbative Corrections
- 4.9 Unconventional SCF Calculations
- 4.10 Ground State Method Summary
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5 Density Functional Theory
- 5.1 Introduction
- 5.2 Kohn-Sham Density Functional Theory
- 5.3 Overview of Available Functionals
- 5.4 Basic DFT Job Control
- 5.5 DFT Numerical Quadrature
- 5.6 Range-Separated Hybrid Density Functionals
- 5.7 DFT Methods for van der Waals Interactions
- 5.8 Empirical Corrections for Basis Set Superposition Error
- 5.9 Double-Hybrid Density Functional Theory
- 5.10 Asymptotically Corrected Exchange-Correlation Potentials
- 5.11 Derivative Discontinuity Restoration
- 5.12 Thermally-Assisted-Occupation Density Functional Theory (TAO-DFT)
- 5.13 Methods Based on “Constrained” DFT
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6 Wave Function-Based Correlation Methods
- 6.1 Introduction
- 6.2 Treatment and the Definition of Core Electrons
- 6.3 Møller-Plesset Perturbation Theory
- 6.4 Exact MP2 Methods
- 6.5 Local MP2 Methods
- 6.6 Auxiliary Basis (Resolution of the Identity) MP2 Methods
- 6.7 Attenuated MP2
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6.8 Coupled-Cluster Methods
- 6.8.1 Coupled Cluster Singles and Doubles (CCSD)
- 6.8.2 Quadratic Configuration Interaction (QCISD)
- 6.8.3 Optimized Orbital Coupled Cluster Doubles (OD)
- 6.8.4 Quadratic Coupled Cluster Doubles (QCCD)
- 6.8.5 Resolution of the Identity with CC (RI-CC)
- 6.8.6 Cholesky decomposition with CC (CD-CC)
- 6.8.7 Job Control Options
- 6.8.8 Examples
- 6.9 Non-Iterative Corrections to Coupled Cluster Energies
- 6.10 Coupled Cluster Active Space Methods
- 6.11 Frozen Natural Orbitals in CCD, CCSD, OD, QCCD, and QCISD Calculations
- 6.12 Non-Hartree-Fock Orbitals in Correlated Calculations
- 6.13 Analytic Gradients and Properties for Coupled-Cluster Methods
- 6.14 Memory Options and Parallelization of Coupled-Cluster Calculations
- 6.15 Using single-precision arithmetics in coupled-cluster calculations
- 6.16 Simplified Coupled-Cluster Methods Based on a Perfect-Pairing Active Space
- 6.17 Geminal Models
- 6.18 Variational Two-Electron Reduced-Density-Matrix Methods
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7 Open-Shell and Excited-State Methods
- 7.1 General Excited-State Features
- 7.2 Uncorrelated Wave Function Methods
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7.3 Time-Dependent Density Functional Theory (TDDFT)
- 7.3.1 Brief Introduction to TDDFT
- 7.3.2 TDDFT within a Reduced Single-Excitation Space
- 7.3.3 Job Control for TDDFT
- 7.3.4 TDDFT Coupled with C-PCM for Excitation Energies and Properties Calculations
- 7.3.5 Analytical Excited-State Hessian in TDDFT
- 7.3.6 Calculations of Spin-Orbit Couplings Between TDDFT States
- 7.3.7 Various TDDFT-Based Examples
- 7.4 Non-Orthogonal Configuration Interaction (NOCI)
- 7.5 Maximum Overlap Method (MOM) for SCF Excited States
- 7.6 Restricted Open-Shell Kohn-Sham Method for -SCF Calculations of Excited States
- 7.7 Correlated Excited State Methods: The CIS(D) Family
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7.8 Coupled-Cluster Excited-State and Open-Shell Methods
- 7.8.1 Excited States via EOM-EE-CCSD
- 7.8.2 EOM-XX-CCSD and CI Suite of Methods
- 7.8.3 Spin-Flip Methods for Di- and Triradicals
- 7.8.4 EOM-DIP-CCSD
- 7.8.5 EOM-DEA-CCSD
- 7.8.6 EOM-CC Calculations of Core-Level States: Core-Valence Separation within EOM-CCSD
- 7.8.7 EOM-CC Calculations of Metastable States: Super-Excited Electronic States, Temporary Anions, and More
- 7.8.8 Charge Stabilization for EOM-DIP and Other Methods
- 7.8.9 Frozen Natural Orbitals in CC and IP-CC Calculations
- 7.8.10 Single-precision arithmetics in EOM-CC calculations
- 7.8.11 Approximate EOM-CC Methods: EOM-MP2 and EOM-MP2T
- 7.8.12 Approximate EOM-CC Methods: EOM-CCSD-S(D) and EOM-MP2-S(D)
- 7.8.13 Implicit solvent models in EOM-CC/MP2 calculations.
- 7.8.14 EOM-CC Jobs: Controlling Guess Formation and Iterative Diagonalizers
- 7.8.15 Equation-of-Motion Coupled-Cluster Job Control
- 7.8.16 Examples
- 7.8.17 Non-Hartree-Fock Orbitals in EOM Calculations
- 7.8.18 Analytic Gradients and Properties for the CCSD and EOM-XX-CCSD Methods
- 7.8.19 EOM-CC Optimization and Properties Job Control
- 7.8.20 EOM(2,3) Methods for Higher-Accuracy and Problematic Situations (CCMAN only)
- 7.8.21 Active-Space EOM-CC(2,3): Tricks of the Trade (CCMAN only)
- 7.8.22 Job Control for EOM-CC(2,3)
- 7.8.23 Non-Iterative Triples Corrections to EOM-CCSD and CCSD
- 7.8.24 Potential Energy Surface Crossing Minimization
- 7.8.25 Dyson Orbitals for Ionized or Attached States within the EOM-CCSD Formalism
- 7.8.26 Interpretation of EOM/CI Wave Functions and Orbital Numbering
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7.9 Correlated Excited State Methods: The ADC() Family
- 7.9.1 The Algebraic Diagrammatic Construction (ADC) Scheme
- 7.9.2 Resolution of the Identity ADC Methods
- 7.9.3 Spin Opposite Scaling ADC(2) Models
- 7.9.4 Core-Excitation ADC Methods
- 7.9.5 Spin-Flip ADC Methods
- 7.9.6 Properties and Visualization
- 7.9.7 Excited States in Solution with ADC/SS-PCM
- 7.9.8 Frozen-Density Embedding: FDE-ADC methods
- 7.9.9 ADC Job Control
- 7.9.10 Examples
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7.10 Restricted Active Space Spin-Flip (RAS-SF) and Configuration Interaction (RAS-CI)
- 7.10.1 The Restricted Active Space (RAS) Scheme
- 7.10.2 Second-Order Perturbative Corrections to RAS-CI
- 7.10.3 Short-Range Density Functional Correlation within RAS-CI
- 7.10.4 Excitonic Analysis of the RAS-CI Wave Function
- 7.10.5 Job Control for the RASCI1 Implementation
- 7.10.6 Job Control Options for RASCI2
- 7.10.7 Examples
- 7.11 Core Ionization Energies and Core-Excited States
- 7.12 Real-Time SCF Methods (RT-TDDFT, RT-HF, OSCF2)
- 7.13 Visualization of Excited States
- 8 Basis Sets
- 9 Effective Core Potentials
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10 Exploring Potential Energy Surfaces: Critical Points and Molecular
Dynamics
- 10.1 Equilibrium Geometries and Transition-State Structures
- 10.2 Improved Algorithms for Transition-Structure Optimization
- 10.3 Constrained Optimization
- 10.4 Potential Energy Scans
- 10.5 Intrinsic Reaction Coordinate
- 10.6 Nonadiabatic Couplings and Optimization of Minimum-Energy Crossing Points
- 10.7 Ab Initio Molecular Dynamics
- 10.8 Ab Initio Path Integrals
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11 Molecular Properties and Analysis
- 11.1 Introduction
- 11.2 Wave Function Analysis
- 11.3 Interface to the NBO Package
- 11.4 Orbital Localization
- 11.5 Visualizing and Plotting Orbitals, Densities, and Other Volumetric Data
- 11.6 Spin and Charge Densities at the Nuclei
- 11.7 Atoms in Molecules
- 11.8 Distributed Multipole Analysis
- 11.9 Intracules
- 11.10 Harmonic Vibrational Analysis
- 11.11 Anharmonic Vibrational Frequencies
- 11.12 Linear-Scaling Computation of Electric Properties
- 11.13 NMR and Other Magnetic Properties
- 11.14 Finite-Field Calculation of (Hyper)Polarizabilities
- 11.15 General Response Theory
- 11.16 Electronic Couplings for Electron- and Energy Transfer
- 11.17 Population of Effectively Unpaired Electrons
- 11.18 Molecular Junctions
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12 Molecules in Complex Environments: Solvent Models,
QM/MM and QM/EFP Features, Density Embedding
- 12.1 Introduction
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12.2 Chemical Solvent Models
- 12.2.1 Kirkwood-Onsager Model
- 12.2.2 Polarizable Continuum Models
- 12.2.3 PCM Job Control
- 12.2.4 Linear-Scaling QM/MM/PCM Calculations
- 12.2.5 Isodensity Implementation of SS(V)PE
- 12.2.6 Composite Method for Implicit Representation of Solvent (CMIRS)
- 12.2.7 COSMO
- 12.2.8 SM8, SM12, and SMD Models
- 12.2.9 Langevin Dipoles Model
- 12.2.10 Poisson Boundary Conditions
- 12.3 Stand-Alone QM/MM Calculations
- 12.4 Q-CHEM/CHARMM Interface
- 12.5 Effective Fragment Potential Method
- 12.6 Projector-Based Density Embedding
- 12.7 Frozen-Density Embedding Theory based methods
- 12.8 Polarizable Embedding Model
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13 Fragment-Based Methods
- 13.1 Introduction
- 13.2 Specifying Fragments in the $molecule Section
- 13.3 FRAGMO Initial Guess for SCF Methods
- 13.4 Locally-Projected SCF Methods
- 13.5 The First-Generation ALMO-EDA and Charge-Transfer Analysis (CTA)
- 13.6 Job Control for Locally-Projected SCF Methods
- 13.7 The Second-Generation ALMO-EDA Method
- 13.8 The MP2 ALMO-EDA Method
- 13.9 The Adiabatic ALMO-EDA Method
- 13.10 ALMO-EDA Involving Excited-State Molecules
- 13.11 The Explicit Polarization (XPol) Method
- 13.12 Symmetry-Adapted Perturbation Theory (SAPT)
- 13.13 The XPol+SAPT (XSAPT) Method
- 13.14 Energy Decomposition Analysis based on SAPT/cDFT
- 13.15 The Many-Body Expansion Method
- 13.16 Ab Initio Frenkel Davydov Exciton Model (AIFDEM)
- 13.17 TDDFT for Molecular Interactions
- 13.18 The ALMO-CIS and ALMO-CIS+CT Methods
- A Geometry Optimization with Q-Chem
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B AOInts
- B.1 Introduction
- B.2 Historical Perspective
- B.3 AOInts: Calculating ERIs with Q-Chem
- B.4 Shell-Pair Data
- B.5 Shell-Quartets and Integral Classes
- B.6 Fundamental ERI
- B.7 Angular Momentum Problem
- B.8 Contraction Problem
- B.9 Quadratic Scaling
- B.10 Algorithm Selection
- B.11 More Efficient Hartree–Fock Gradient and Hessian Evaluations
- B.12 User-Controllable Variables
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C Q-Chem Quick Reference
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C.1 Q-Chem Text Input Summary
- C.1.1 Keyword: $molecule
- C.1.2 Keyword: $rem
- C.1.3 Keyword: $basis
- C.1.4 Keyword: $comment
- C.1.5 Keyword: $ecp
- C.1.6 Keyword: $empirical_dispersion
- C.1.7 Keyword: $external_charges
- C.1.8 Keyword: $intracule
- C.1.9 Keyword: $isotopes
- C.1.10 Keyword: $multipole_field
- C.1.11 Keyword: $nbo
- C.1.12 Keyword: $occupied
- C.1.13 Keyword: $opt
- C.1.14 Keyword: $svp
- C.1.15 Keyword: $svpirf
- C.1.16 Keyword: $plots
- C.1.17 Keyword: $localized_diabatization
- C.1.18 Keyword: $van_der_waals
- C.1.19 Keyword: $xc_functional
- C.2 Geometry Optimization with General Constraints
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C.3 $rem Variable List
- C.3.1 General
- C.3.2 SCF Control
- C.3.3 DFT Options
- C.3.4 Large Molecules
- C.3.5 Correlated Methods
- C.3.6 Correlated Methods Handled by CCMAN and CCMAN2
- C.3.7 Perfect pairing, Coupled cluster valence bond, and related methods
- C.3.8 Excited States: CIS, TDDFT, SF-XCIS and SOS-CIS(D)
- C.3.9 Excited States: EOM-CC and CI Methods
- C.3.10 Geometry Optimizations
- C.3.11 Vibrational Analysis
- C.3.12 Reaction Coordinate Following
- C.3.13 NMR Calculations
- C.3.14 Wave function Analysis and Molecular Properties
- C.3.15 Symmetry
- C.3.16 Printing Options
- C.3.17 Resource Control
- C.4 Alphabetical Listing of $rem Variables
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C.1 Q-Chem Text Input Summary