Energy-based atomistic properties#
The energy-based properties are based on the energy terms of the xTB Hamiltonian. An atomistic partitioning is used to compute the properties. By exposing all terms of the energy term, a ML model could combine those terms to build a better fitting model. The following energy terms are computed:
Dictionary Key |
Description |
Equation |
|---|---|---|
|
Extended Hueckel term |
\(E_{A,\text{EHT}}= \sum_{\kappa \in A} \sum_{\kappa} P_{\kappa\lambda} H_{\kappa\lambda}\) |
|
Repulsion term |
\(E_{A,\text{rep}}= \sum_{B\neq A}^{M} \frac{1}{2} \frac{Y_A^{\text{eff}} Y_B^{\text{eff}}}{R_{AB}}e^{(\alpha_A\alpha_B)^{0.5}(R_{AB})^{k_{\text{rep}}}}\), see also Repulsive contributions |
|
isotropic electrostatic and exchange correlation term |
\(E_{A,\text{IES+IXC}}=\frac{1}{2}\sum_{B\neq A}\sum_{l\in A}\sum_{l'\in B} q_{A,l} q_{B,l'} \gamma_{AB,ll'} + \frac{1}{3}\sum_{l\in A} \Gamma_{A,l}q_{A,l}^3\), see also Electrostatic interactions |
|
anisotropic exchange correlation term |
\(E_{A,\text{AXC}} = \left(f_{\text{XC}}^{\mu_A}|\boldsymbol{\mu}_A|^2+f^{\Theta_A}_{\text{XC}}||\boldsymbol{\Theta}_A||^2\right)\) |
|
anisotropic electrostatic term |
see \(E_{AES}\) definition in Electrostatic interactions, while only summing up over atom B |
|
two body dispersion term |
\(E_{A,\text{disp}}^{(2)} = \sum_{A\neq B}\sum_{n=6,8} - s_n \frac{1}{2} \frac{C_n^{AB}(q_a,CN^A_{\text{cov}},q_b,CN^B_{\text{cov}})}{R^n_{AB}} f^{\text{log,BJ}}_n(R_{AB})\) |
|
three body dispersion term |
\(E_{A,\text{disp}}^{(3)} = \sum_{B\neq A} \sum_{C\neq B\neq A}-s_9\frac{1}{3} \frac{(3 \cos(\theta_{ABC}) \cos(\theta_{BCA}) \cos(\theta_{CAB})+1)C_9^{ABC} (CN_{\text{cov}}^A,CN_{\text{cov}}^B,CN_{\text{cov}}^C)}{(R_{AB}R_{AC}R_{BC})^3} \cdot f^{\text{log,zero}}_9(R_{AB},R_{AC},R_{BC})\) |
|
Halogen bond term |
|
|
Sum of energy terms |
|
|
weight of atom in total energy |
\(w_{A,\text{tot}} = \frac{E_{A,\text{tot}}}{E_{\text{tot}}}\) |
Extended energy-based properties#
There are no extended energy-based properties available.