We are proposing a new computational thermochemistry protocol denoted W3 theory, as a successor to W1 and W2 theory proposed earlier [Martin and De Oliveira, J. Chem. Phys. 111, 1843 (1999)]. The new method is both more accurate overall (error statistics for total atomization energies approximately cut in half) and more robust (particularly towards systems exhibiting significant nondynamical correlation) than W2 theory. The cardinal improvement rests in an approximate account for post-CCSD(T) correlation effects. Iterative T_3 (connected triple excitations) effects exhibit a basis set convergence behavior similar to the T_3 contribution overall. They almost universally decrease molecular binding energies. Their inclusion in isolation yields less accurate results than CCSD(T) nearly across the board: it is only when T_4 (connected quadruple excitations) effects are included that superior performance is achieved. $T_4$ effects systematically increase molecular binding energies. Their basis set convergence is quite rapid, and even CCSDTQ/cc-pVDZ scaled by an empirical factor of 1.2532 will yield a quite passable quadruples contribution. The effect of still higher-order excitations was gauged for a subset of molecules (notably the eight-valence electron systems): T_5 (connected quintuple excitations) contributions reach 0.3 kcal/mol for the pathologically multireference X ^1Σ^+_g state of C_2 but are quite small for other systems. A variety of avenues for achieving accuracy beyond that of W3 theory were explored, to no significant avail. W3 thus appears to represent a good compromise between accuracy and computational cost for those seeking a robust method for computational thermochemistry in the kJ/mol accuracy range on small systems.
Structure and thermochemistry of K$_2$Rb, KRb$_2$ and K$_2$Rb$_2$
超冷极性分子的形成和相互作用是一个活跃的研究课题。了解可能的反应路径和分子组合需要准确的研究片段和产品的能量。我们精确地计算了KRb与KRb反应生成的三聚体和四聚体以及相应的孤立原子的梯度优化基态结构和零点校正原子化能。K-${}_2$-Rb和K-Rb-${}_2$三聚体在$C_{2v}$构型下具有全局极小值，原子化能分别为6065和5931 cm ${}^{-1}$，而四聚体具有两个稳定的平面结构，分别为$D_{2h}$和$C_s$对称，原子化能分别为11131 cm ${}^{-1}$和11133 cm ${}^{-1}$.我们计算了KRb+KRb到K $_2+$ Rb $_2$反应的最小能量反应路径，发现它是无势垒的。
Benchmark thermochemistry of the C_nH_{2n+2} alkane isomers (n=2--8) and performance of DFT and composite ab initio methods for dispersion-driven isomeric equilibria
本文用W_4、W_3.2lite和W_1h理论重新研究了八碳以下直链和支链烷烃的热化学。通过等键和次同键反应获得了"准W4"原子化能。我们在0 K时的最佳原子化能量（kcal/mol）为：1220.04正丁烷，1497.01正戊烷，1774.15正己烷，2051.17正庚烷，2328.30正辛烷，1221.73异丁烷，1498.27异戊烷，1501.01新戊烷，1775.22异己烷，1774.61 3-甲基戊烷，1775.67二异丙基、1777.27新己烷、2052.43异庚烷、2054.41新庚烷、2330.67异辛烷和2330.81六甲基乙烷。我们对$ΔH^\circ_{f,298K}$的最佳估计为：-30.00正丁烷、-34.84正戊烷、-39.84正己烷、-44.74正庚烷、-49.71正辛烷、-32.01异丁烷、-36.49异戊烷、-39.69新戊烷、-41.42异己烷、-40.72 3-甲基戊烷、-42.08二异丙基、-43.77新己烷，-46.43异庚烷、-48.84新庚烷、-53.29异辛烷和-53.68六甲基乙烷。这些是在极好的协议（通常优于1 kJ/mol），在298 K的实验生成热从CCCBDB和/或NIST化学网络图书数据库。然而，在0 K的理论和实验（1.1千卡/摩尔）之间的一个很大的差异观察到只有新戊烷。这种偏差主要是由于在计算0 K CCCBDB值时使…
Basis set convergence and extrapolation of connected triple excitation contributions (T) in computational thermochemistry: the W4-17 benchmark with up to k functions
Molecular reference corrections for quantum Monte Carlo adsorption energies
SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory（斯坦福直线加速器中心界面科学与催化中心）；Department of Chemical Engineering, Stanford University（斯坦福大学化学工程系）；SLAC National Accelerator Laboratory（斯坦福直线加速器中心）；Stanford University（斯坦福大学）
Assessment of W1 and W2 theories for the computation of electron affinities, ionization potentials, heats of formation, and proton affinities
本文介绍了两种新的{ \em ab initio}计算热化学方法，W1和W2理论[J.M.L. Martin和G. de Oliveira，J.Chem.Phys.111，1843（1999）]，评估了由G2-1和G2-2集合中的电离势和电子亲合势以及G2 -1和G2 -2集合的子集中的生成热组成的热化学数据的放大样本。我们发现W1理论对于电离势和电子亲合势的精确度比常用的（并且更便宜的）计算热化学方案（如G2，G3和CBS-QB 3）高出几倍：W2理论对于电子亲合势略有改善，但对于电离势没有显著改善。使用两点的$A+B/L^5$，而不是一个三点的$A+B/C^L$外推的SCF组件大大提高了数值稳定性的W1方法的系统与缓慢的基组收敛。包含一阶自旋轨道耦合对于精确的电离势和涉及简并电子态的电子亲合势是必不可少的：内壳层相关对于电离势比电子亲合势更重要，而标量相对论效应则需要最高的精度。G2-1生成热与实验的平均偏差在平均实验不确定度范围内。W1理论似乎是一个有价值的工具，获得基准质量的质子亲和力。
Quantum Ring-Polymer Contraction Method: Including nuclear quantum effects at no additional computational cost in comparison to ab-initio molecular dynamics
MACE-POLAR-1: A Polarisable Electrostatic Foundation Model for Molecular Chemistry
Engineering Laboratory, University of Cambridge, Trumpington St, Cambridge, UK；Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, UK；Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge, UK；Scientific Computing Department, Science；Technology Facilities Council, Daresbury Laboratory, Keckwick Lane, Daresbury WA4 4AD, UK；Department of Physics；Astronomy, University College London, 7-19 Gordon St, London WC1H 0AH, United Kingdom；Initiative for Computational Catalysis, Flatiron Institute, 160 5th Avenue, New York, NY 10010；School of Natural；Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK；Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz, Germany
