van der Waals density functional with corrected C6 coefficients
van der Waals density functional with corrected C6 coefficients
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DOI：
10.1103/physrevb.99.195418
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发表时间：
2019-05
影响因子：
3.7
通讯作者：
K. Berland;K. Berland;Debajit Chakraborty;T. Thonhauser
中科院分区：
文献类型：
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作者：
K. Berland;K. Berland;Debajit Chakraborty;T. Thonhauser
非局部货车德瓦尔斯密度泛函（vdw-DF）自2004年成立以来，由于其严格从多体出发的基于约束的形式主义，取得了巨大的成功。然而，虽然vdw-DF可以描述结合能和结构的货车德瓦尔斯配合物和混合系统具有良好的准确性，一个长期存在的批评-也是自成立以来-一直是C_6 $系数，从vdw-DF框架是很大程度上不准确，可以是错误的两倍以上。长期以来，人们一直认为，这种未能描述的C_6 $系数是一个概念上的缺陷的基础等离子体框架用于推导vdw-DF。我们在这里证明，这是不是这样的情况下，准确的C_6 $系数，可以得到不牺牲的准确性，在结合分离从一个修改后的框架，是完全一致的约束条件和设计理念的原始vdW-DF配方。我们的设计利用了等离子体色散模型$\omega_{\mathbf{q}}$中的自由度，修改了远程货车德瓦尔斯相互作用的强度和从长到短分离的交叉，并将额外的参数调整到参考系统。对一系列不同的体系进行了测试，我们不仅证实了对C_6系数的描述有了很大的改进，而且我们还发现了对分子二聚体和其他体系的优异性能。这一发展的重要性不一定是特定的方面，如$C_6$系数或结合能得到改善，而是我们的发现打开了大门，在完全相同的约束为基础的非本地的框架内，使vdw-DF如此成功的摆在首位，一个完全未探索的方向进一步的概念发展。
The non-local van der Waals density functional (vdW-DF) has had tremendous success since its inception in 2004 due to its constraint-based formalism that is rigorously derived from a many-body starting point. However, while vdW-DF can describe binding energies and structures for van der Waals complexes and mixed systems with good accuracy, one long-standing criticism---also since its inception---has been that the $C_6$ coefficients that derive from the vdW-DF framework are largely inaccurate and can be wrong by more than a factor of two. It has long been thought that this failure to describe the $C_6$ coefficients is a conceptual flaw of the underlying plasmon framework used to derive vdW-DF. We prove here that this is not the case and that accurate $C_6$ coefficient can be obtained without sacrificing the accuracy at binding separations from a modified framework that is fully consistent with the constraints and design philosophy of the original vdW-DF formulation. Our design exploits a degree of freedom in the plasmon-dispersion model $\omega_{\mathbf{q}}$, modifying the strength of the long-range van der Waals interaction and the cross-over from long to short separations, with additional parameters tuned_ to reference systems. Testing the new formulation for a range of different systems, we not only confirm the greatly improved description of $C_6$ coefficients, but we also find excellent performance for molecular dimers and other systems. The importance of this development is not necessarily that particular aspects such as $C_6$ coefficients or binding energies are improved, but rather that our finding opens the door for further conceptual developments of an entirely unexplored direction within the exact same constrained-based non-local framework that made vdW-DF so successful in the first place.