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nuclear-electronic_orbital_method [2025/05/21 12:14] – rmatanuclear-electronic_orbital_method [2025/05/21 12:36] (current) – [Density fitting NEO-DFT] rmata
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 ====== Nuclear-electronic orbital (NEO) method ====== ====== Nuclear-electronic orbital (NEO) method ======
  
-The [[https://doi.org/10.1021/acs.chemrev.9b00798|Nuclear-electron orbital (NEO)]] method pioneered by Hammes-Schiffer and coworkers is available in **''Molpro''** for density fitted spin-restricted NEO-Hartree-Fock as well as a local-density fitting variant. It allows to handle a selected number of hydrogen nuclei as quantum particles by building a second Fock-matrix for the latter, coupling both subsystems (electrons and quantum protons) by a Coulomb operator. Further information about the method can be found [[https://doi.org/10.1021%2Facs.jctc.3c01055|here]].+The [[https://doi.org/10.1021/acs.chemrev.9b00798|Nuclear-electron orbital (NEO)]] method pioneered by Hammes-Schiffer and coworkers is available in **''Molpro''** for (local) density fitted spin-restricted NEO-Hartree-Fock as well as NEO-RKS. It allows to handle a selected number of hydrogen nuclei as quantum particles by building a second Fock-matrix for the latter, coupling both subsystems (electrons and quantum protons) by a Coulomb operator. Further information about the method can be found [[https://doi.org/10.1021%2Facs.jctc.3c01055|here]].
  
   * **''DF-NEO-RHF'', //options//** calls the density-fitted NEO-Hartree-Fock program   * **''DF-NEO-RHF'', //options//** calls the density-fitted NEO-Hartree-Fock program
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   * **''DF-NEO-RKS'', //options//** calls the density-fitted NEO-DFT program   * **''DF-NEO-RKS'', //options//** calls the density-fitted NEO-DFT program
  
-Currently, both options require the **''gdirect''** option and are not available with symmetry.+Currently, all NEO programs require the use of the **''gdirect''** option and are not available with symmetry.
  
 ===== Density fitting NEO-Hartree-Fock ===== ===== Density fitting NEO-Hartree-Fock =====
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 ===== Density fitting NEO-DFT ===== ===== Density fitting NEO-DFT =====
  
-The NEO-DFT program with density fitting for electron-repulsion integrals is available through+The spin-restricted NEO-DFT program with density fitting for electron-repulsion integrals is available through
  
 <code> <code>
-{grid,name=SG3} 
 DF-NEO-RKS,functional,options DF-NEO-RKS,functional,options
 NEOEPC,epc-functional NEOEPC,epc-functional
 </code> </code>
  
 +Currently only standard grids are supported (''SG1'', ''SG2'' and ''SG3''). The use of ''SG3'' is recommended for its numerical stability. If no grid is defined, the program defaults to ''SG2'' and issues a warning. The DFT functional for electronic exchange and correlation is defined as an option (//functional//), similar to a regular DFT calculation. However, in the case of NEO-DFT one also requires the definition of an electron-proton correlation (epc) functional (//epc-functional//). The program currently supports ''epc17.1'', ''epc17.2'', ''epc18.1'' and ''epc18.2'', as provided through the libxc library. We recommend the use of the epc17.2 functional for NEO-DFT calculations in general.
 +
 +The definition of the quantum nuclei as well as the thresholds for the convergence of the nuclear cycles follows the same procedure as NEO-HF.
 ===== NEO specific options ===== ===== NEO specific options =====
  
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 </code> </code>
  
-The second example shows the input of a **''LDF-NEO-RHF''** computation of the same molecule starting from a prior RHF calculation. In this example a [[dump_density_or_orbital_values_cube|cube]] file is requested. This will output the quantum nuclei density.+The second example shows the input of a **''DF-NEO-RKS''** calculation. The grid used is ''SG3'', with the B3LYP functional used for the electron-electron exchange-correlation and epc17.2 for the electron-proton correlation. 
 + 
 +<code> 
 +memory,50,m 
 +gdirect 
 +nosym 
 +noextra 
 +geometry={ 
 +3 
 + 
 +H1  -3.5008791    1.2736107    0.7596000 
 +H2  -4.9109791    1.2967107    0.1521000 
 +O   -3.9840791    1.3301107   -0.0574000 
 +} 
 +charge=0 
 +basis={ 
 +default=cc-pvdz 
 +set,nucbas 
 +default=neo-basis 
 +H1=pb4-D 
 +H2=pb4-D 
 +set,nucfit, context=JKFIT 
 +default=cc-pvdz 
 +H1=10s10p10d10f 
 +H2=10s10p10d10f 
 +} 
 +{grid,name=SG2} 
 +{df-rks,b3lyp,df_basis=cc-pvdz} 
 +qnuc,H1,H2 
 +{df-neo-rks,b3lyp,df_basis=cc-pvtz 
 +NEOEPC,EPC17.2 
 +} 
 +</code> 
 + 
 +The following example shows the input of a **''LDF-NEO-RHF''** computation of the same molecule starting from a prior RHF calculation. In this example a [[dump_density_or_orbital_values_cube|cube]] file is requested. This will output the quantum nuclei density.
  
 <code> <code>
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 H1=10s10p10d10f H1=10s10p10d10f
 } }
 +
 +{rhf}
  
 qnuc,H1 qnuc,H1