Taniguchi Masateru, Kawai Tomoji
Nanoscience and Nanotechnology Center, The Institute of Scientific and Industrial Research, Osaka University, Osaka 567-0047, Japan.
Phys Rev E Stat Nonlin Soft Matter Phys. 2004 Jul;70(1 Pt 1):011913. doi: 10.1103/PhysRevE.70.011913. Epub 2004 Jul 29.
The electronic band structures and total density of states based on a density-functional theory are performed on four deoxyribonucleic acid (DNA) molecules: namely, A- and B-type DNA where a single pitch is formed by 11 and 10 base pairs, respectively, of Poly (dA) *Poly (dT) and Poly (dG) *Poly (dC). Poly (dA) *Poly (dT) is a DNA where one single strand consists only of adenine (A) and the other single strand consists only of thymine (T), while Poly (dG) *Poly (dC) is a DNA where one single strand consists only of guanine (G) and the other of cytosine (C). A- and B-Poly (dA) *Poly (dT) and A- and B-Poly (dG) *Poly (dC) DNA. Compared in the same structure, the band gap of Poly (dA) *Poly (dT) is larger than that of Poly (dG) *Poly (dC). The highest occupied molecular orbitals (HOMO's) of Poly (dA) *Poly (dT) and Poly (dG) *Poly (dC) are formed by adenine's and guanine's HOMO, respectively, regardless of the structure type. On the other hand, the lowest unoccupied molecular orbitals (LUMO's) of DNA of both types are formed by the orbitals of Na and P O4, though the LUMO's of B-Poly (dA) *Poly (dT) and B-Poly (dG) *Poly (dG) are formed by thymine's and cytosine's LUMO when the DNA-DNA distance is more than 3 nm. The minimum energy gap between the valence edge and the empty state of Na and PO4 is 0.9 eV in A-Poly (dG) *Poly (dC). The narrow bandwidth of the valence and conduction bands show that the conduction arises not from band transport but a hopping mechanism in the presence of doping.
基于密度泛函理论，对四种脱氧核糖核酸（DNA）分子进行了电子能带结构和态密度计算：即A - 型和B - 型DNA，其中Poly（dA）*Poly（dT）和Poly（dG）*Poly（dC）的单螺距分别由11个和10个碱基对形成。Poly（dA）*Poly（dT）是一种DNA，其一条单链仅由腺嘌呤（A）组成，另一条单链仅由胸腺嘧啶（T）组成，而Poly（dG）*Poly（dC）是一种DNA，其一条单链仅由鸟嘌呤（G）组成，另一条由胞嘧啶（C）组成。A - 和B - Poly（dA）*Poly（dT）以及A - 和B - Poly（dG）*Poly（dC）DNA。在相同结构下比较，Poly（dA）*Poly（dT）的带隙大于Poly（dG）*Poly（dC）的带隙。Poly（dA）*Poly（dT）和Poly（dG）*Poly（dC）的最高占据分子轨道（HOMO）分别由腺嘌呤和鸟嘌呤的HOMO形成，与结构类型无关。另一方面，两种类型DNA的最低未占据分子轨道（LUMO）由Na和PO4的轨道形成，不过当DNA - DNA距离大于3 nm时，B - Poly（dA）*Poly（dT）和B - Poly（dG）*Poly（dG）的LUMO由胸腺嘧啶和胞嘧啶的LUMO形成。在A - Poly（dG）*Poly（dC）中，价带边缘与Na和PO4的空态之间的最小能隙为0.9 eV。价带和导带的窄带宽表明，在存在掺杂的情况下，导电不是由带传输引起的，而是由跳跃机制引起的。
