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--- nuclear-electronic_orbital_method [2023/08/21 09:36] – [NEO examples] rmatalhaseck
+++ nuclear-electronic_orbital_method [2024/01/29 13:29] – [Bibliography] rmatalhaseck
@@ Line 1: / Line 1: @@
-====== Nuclear-electron 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 in a  [[https://doi.org/10.21203/rs.3.rs-3231458/v1|preprint]].
+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]].
   * **''DF-NEO-RHF'', //options//** calls the density-fitted NEO-Hartree-Fock program
@@ Line 96: / Line 96: @@
   * **''NEORD'', //number//** sets the start for the fast rotational update of the orbitals in the local version
   * **''NOBLOCKDIAG''** disables the block diagonalization of the nuclear starting guess (this is generally not recommended!!)
+  * **''NEOMIXBAS''** enables the use of user-defined mixed basis sets (see example for use)
+===== Adaptive NEO =====
+Optimization of quantum nuclei positions with the adaptive NEO approach, where the nuclear centroids are computed on-the-fly during the SCF iterations. This procedure is available by using the
+<code>
+ADAPTIVE
+</code>
+keyword in the NEO program input card.
+==== Threshold ====
+The thresholds for the convergence criteria of the nuclear centers during an adaptive NEO computation can be adjusted with the following keyword
+  * **''ADTHRES'', //number//** sets the convergence threshold for the nuclear centers in atomic units
+  * **''ADITER'', //number//** sets the initial iteration for the start of the adaptive procedure (default=2)
+==== Damping ====
+The shift of the nuclear basis function center towards the charge centroid can be damped with the following keyword
+  * **''ADDUMP'', //number//** sets the damping factor of the nuclear centroid shift
 ===== NEO examples =====
@@ Line 142: / Line 162: @@
 </code>
-The second example shows the input of a **''LDF-NEO-RHF''** computation of the same molecule starting from a prior RHF calculation.
+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.
 <code>
@@ Line 179: / Line 199: @@
 {ldf-neo-rhf,maxdis=10,maxit=200,df_basis=cc-pvdz}
-{cube,nuclear_density.cube;density,2102.2}
+{cube,nuclear.cube;density,2102.2}
 </code>
+The following example shows a NEO calculation, where a user-defined mixed basis set is used. Thereby, the electronic basis set at the quantum nuclei is larger than for regular hydrogen atoms. The use of the **''NEOMIXBAS''** requires the additional definition of the **''elebas''** and **''elefit''** basis sets as shown below.
+<code>
+memory,50,m
+gdirect
+nosym
+geometry={
+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-pvtz
+H1=cc-pv5z
+set,nucbas
+default=neo-basis
+H1=pb4-f2
+set,nucfit
+default=neo-basis
+H1=10s10p10d10f
+set,elebas
+default=cc-pvtz
+H1=cc-pv5z
+set,elefit,context=jkfit
+default=cc-pvtz
+H1=cc-pv5z
+}
+qnuc,H1
+{df-neo-rhf,maxdis=10,maxit=1000,df_basis=elefit
+neoit,100
+neothre,1.d-6
+neothrie,1.d-8
+neothrin,1.d-8
+neothrd,1.d-8
+neothrg,1.d-8
+neoatden
+neomixbas
+}
+</code>
+The example below shows the input for an adaptive NEO calculation, where the nuclear basis function centers convergence is set below 1E-5 bohr and a damping factor of 0.5 is applied.
+<code>
+memory,50,m
+gdirect
+nosym
+geometry={
+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-f2
+set,nucfit
+default=neo-basis
+H1=10s10p10d10f
+}
+qnuc,H1
+{df-neo-rhf,maxdis=10,maxit=500,df_basis=cc-pvdz
+neoit,100
+neothre,1.d-6
+neothrie,1.d-8
+neothrin,1.d-8
+neothrd,1.d-8
+neothrg,1.d-8
+adaptive
+adthres,1.d-5
+addump,0.5
+}
+</code>
 ===== Bibliography =====
@@ Line 196: / Line 311: @@
 ===(L)DF-NEO-RHF===
-Lukas Hasecke, and Ricardo A. Mata [[https://doi.org/10.21203/rs.3.rs-3231458/v1|Nuclear quantum effects made accessible: local-density fitting in multicomponent methods]] //Research Square// **2023** preprint.
+Lukas Hasecke, and Ricardo A. Mata [[https://doi.org/10.1021/acs.jctc.3c01055|Nuclear Quantum Effects Made Accessible: Local Density Fitting in Multicomponent Methods]] //J. Chem. Theory Comput.// **2023** //19// (22), 8223–8233.