Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA.
J Chem Phys. 2012 Jun 21;136(23):234301. doi: 10.1063/1.4725496.
A recently developed method to represent adiabatic electronic states coupled by conical intersections has been used to construct a full six-dimensional quasi-diabatic representation of the 1(1)A and 2(1)A states of NH(3). This representation is expected to be appropriate to simulate the photodissociation of ammonia when it is excited to the 2(1)A electronic state. In this work, the electronic structure aspects of this quasi-diabatic representation are analyzed. This representation is then used as the basis for a simulation of the à ← X absorption spectrum, dominated by a progression in the v(2) mode, using a full six-dimensional quantum mechanical treatment of the nuclear motion. Results are reported for both NH(3) and ND(3). This simulation provides the most accurate computational determination of this absorption spectrum reported to date. These results serve to validate the quasi-diabatic representation and set the stage for subsequent studies of vibrationally mediated photodissociation of NH(3).
最近开发的一种表示通过圆锥交叉点耦合的绝热电子态的方法已被用于构建 NH(3) 的 1(1)A 和 2(1)A 态的完整六维准绝热表示。该表示预计适用于模拟当氨被激发到 2(1)A 电子态时的光解。在这项工作中，分析了这种准绝热表示的电子结构方面。然后，该表示被用作使用核运动的全六维量子力学处理来模拟主要由 v(2)模式进展主导的 Ã ← X 吸收光谱的基础。报告了 NH(3) 和 ND(3) 的结果。该模拟提供了迄今为止报道的该吸收光谱的最准确的计算确定。这些结果验证了准绝热表示，并为随后研究 NH(3) 的振动介导光解奠定了基础。
