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O2 is Cubic alpha N2 structured and crystallizes in the orthorhombic Pbca space group. The structure is zero-dimensional and consists of eight trioxidane molecules. there are two inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one O atom. The O–O bond length is 1.28 Å. In the second O site, O is bonded in a bent 120 degrees geometry to two equivalent O atoms.
H2SO4 is Protactinium-like structured and crystallizes in the monoclinic Cc space group. The structure is zero-dimensional and consists of four sulfuric acid molecules. there are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. S6+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of S–O bond distances ranging from 1.44–1.58 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one S6+ atom. In the second O2- site, O2- is bonded in a distorted water-like geometry to one H1+ and one S6+ atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to one H1+ and one S6+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one S6+ atom.
H2SO4 crystallizes in the monoclinic Cc space group. The structure is zero-dimensional and consists of four sulfuric acid molecules. there are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. S6+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of S–O bond distances ranging from 1.43–1.59 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one S6+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one H1+ and one S6+ atom. In the third O2- site, O2- is bonded in a water-like geometry to one H1+ and one S6+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one S6+ atom.
H4SO5 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four sulfuric acid, monohydrate molecules. there are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the third H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.16 Å) and one longer (1.28 Å) H–O bond length. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. S6+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of S–O bond distances ranging from 1.44–1.60 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one S6+ atom. In the second O2- site, O2- is bonded in a trigonal non-coplanar geometry to three H1+ atoms. In the third O2- site, O2- is bonded in a single-bond geometry to one S6+ atom. In the fourth O2- site, O2- is bonded in a water-like geometry to one H1+ and one S6+ atom. In the fifth O2- site, O2- is bonded in a water-like geometry to one H1+ and one S6+ atom.
S crystallizes in the trigonal P3 space group. The structure is zero-dimensional and consists of six trisulfane molecules. there are three inequivalent S sites. In the first S site, S is bonded in a single-bond geometry to one S atom. The S–S bond length is 1.94 Å. In the second S site, S is bonded in a bent 120 degrees geometry to two S atoms. The S–S bond length is 1.93 Å. In the third S site, S is bonded in a single-bond geometry to one S atom.
H2O is Indium structured and crystallizes in the monoclinic Cc space group. The structure is zero-dimensional and consists of four water water molecules. there are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. In the second H1+ site, H1+ is bonded in a distorted single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fourth H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.01 Å) and one longer (1.65 Å) H–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted water-like geometry to two H1+ atoms. In the second O2- site, O2- is bonded in a distorted water-like geometry to three H1+ atoms.
H2O is Keatite structured and crystallizes in the tetragonal P4_12_12 space group. The structure is zero-dimensional and consists of twelve water molecules. there are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. O2- is bonded in a water-like geometry to two H1+ atoms.
H2O is beta Tridymite structured and crystallizes in the orthorhombic Cmc2_1 space group. The structure is zero-dimensional and consists of eight water molecules. there are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. O2- is bonded in a water-like geometry to two H1+ atoms.
C3N is Hg_xSn structured and crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four trimethylamine molecules. there are two inequivalent C1+ sites. In the first C1+ site, C1+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.33 Å. In the second C1+ site, C1+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.43 Å. N3- is bonded in a distorted T-shaped geometry to three C1+ atoms.
C3N is Potassium Silver Cyanide-derived structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional and consists of one ammonia molecule, eight methane molecules, one C4N cluster, and one C2N framework. In the C4N cluster, C1+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.39 Å. N3- is bonded in a square co-planar geometry to four equivalent C1+ atoms. In the C2N framework, there are nine inequivalent C1+ sites. In the first C1+ site, C1+ is bonded in a linear geometry to two N3- atoms. There is one shorter (1.24 Å) and one longer (1.81 Å) C–N bond length. In the second C1+ site, C1+ is bonded in a linear geometry to two N3- atoms. There is one shorter (1.24 Å) and one longer (1.81 Å) C–N bond length. In the third C1+ site, C1+ is bonded in a linear geometry to two N3- atoms. There is one shorter (1.56 Å) and one longer (2.15 Å) C–N bond length. In the fourth C1+ site, C1+ is bonded in a linear geometry to two N3- atoms. There is one shorter (1.56 Å) and one longer (2.15 Å) C–N bond length. In the fifth C1+ site, C1+ is bonded in a linear geometry to two N3- atoms. There is one shorter (1.56 Å) and one longer (2.15 Å) C–N bond length. In the sixth C1+ site, C1+ is bonded in a linear geometry to two N3- atoms. There is one shorter (1.69 Å) and one longer (2.02 Å) C–N bond length. In the seventh C1+ site, C1+ is bonded in a linear geometry to two N3- atoms. There is one shorter (1.69 Å) and one longer (2.02 Å) C–N bond length. In the eighth C1+ site, C1+ is bonded in a linear geometry to two N3- atoms. There is one shorter (1.69 Å) and one longer (2.02 Å) C–N bond length. In the ninth C1+ site, C1+ is bonded in a linear geometry to two N3- atoms. There is one shorter (1.69 Å) and one longer (2.02 Å) C–N bond length. There are four inequivalent N3- sites. In the first N3- site, N3- is bonded in a square co-planar geometry to four C1+ atoms. In the second N3- site, N3- is bonded in a square co-planar geometry to four C1+ atoms. In the third N3- site, N3- is bonded in a linear geometry to two C1+ atoms. In the fourth N3- site, N3- is bonded in an octahedral geometry to six C1+ atoms.
O2 is gamma plutonium-like structured and crystallizes in the triclinic P1 space group. The structure is zero-dimensional and consists of four trioxidane molecules. there are two inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one O atom. The O–O bond length is 1.28 Å. In the second O site, O is bonded in a bent 120 degrees geometry to two equivalent O atoms. There is one shorter (1.28 Å) and one longer (1.29 Å) O–O bond length.
C3N is beta Np structured and crystallizes in the orthorhombic P2_12_12_1 space group. The structure is zero-dimensional and consists of four aziridine, 1-methyl- molecules. there are three inequivalent C1+ sites. In the first C1+ site, C1+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.40 Å. In the second C1+ site, C1+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.45 Å. In the third C1+ site, C1+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.44 Å. N3- is bonded in a 3-coordinate geometry to three C1+ atoms.
NO crystallizes in the monoclinic C2/c space group. The structure is zero-dimensional and consists of four nitramide molecules. there are two inequivalent N sites. In the first N site, N is bonded in a single-bond geometry to one N atom. The N–N bond length is 1.38 Å. In the second N site, N is bonded in a distorted trigonal planar geometry to one N and two equivalent O atoms. Both N–O bond lengths are 1.24 Å. O is bonded in a single-bond geometry to one N atom.
O2 crystallizes in the tetragonal P4_12_12 space group. The structure is zero-dimensional and consists of four trioxidane molecules. there are two inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one O atom. The O–O bond length is 1.29 Å. In the second O site, O is bonded in a bent 120 degrees geometry to two equivalent O atoms.
RuN2ClN2ClSO2 crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four sulfur dioxide molecules, four N2Cl clusters, and four RuN2Cl clusters. In each N2Cl cluster, N1+ is bonded in a single-bond geometry to one Cl1- atom. The N–Cl bond length is 1.53 Å. Cl1- is bonded in a 2-coordinate geometry to two equivalent N1+ atoms. In each RuN2Cl cluster, Ru4+ is bonded in a trigonal non-coplanar geometry to two equivalent N1+ and one Cl1- atom. Both Ru–N bond lengths are 1.72 Å. The Ru–Cl bond length is 2.26 Å. N1+ is bonded in a single-bond geometry to one Ru4+ atom. Cl1- is bonded in a single-bond geometry to one Ru4+ atom.
Ti2OCl6CO2(HSeOCl2)2(SeCl)2(Cl2)2 crystallizes in the monoclinic P2/c space group. The structure is zero-dimensional and consists of two carbon dioxide molecules, four chlorine molecules, four chloroselenurane molecules, two HSeOCl2 clusters, and two Ti2OCl6 clusters. In each HSeOCl2 cluster, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. Se3+ is bonded in a distorted L-shaped geometry to one O2- and one Cl1- atom. The Se–O bond length is 1.81 Å. The Se–Cl bond length is 2.39 Å. O2- is bonded in a distorted water-like geometry to one H1+ and one Se3+ atom. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a distorted linear geometry to two Cl1- atoms. There are one shorter (2.08 Å) and one longer (2.92 Å) Cl–Cl bond lengths. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Se3+ and one Cl1- atom. In each Ti2OCl6 cluster, Ti4+ is bonded to one O2- and three Cl1- atoms to form corner-sharing TiCl3O tetrahedra. The Ti–O bond length is 1.79 Å. There are two shorter (2.19 Å) and one longer (2.21 Å) Ti–Cl bond lengths. O2- is bonded in a linear geometry to two equivalent Ti4+ atoms. There are three inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Ti4+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Ti4+ atom. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one Ti4+ atom.
A discussion is presented of IR spectroscopy, particularly high-resolution spectroscopy in the approximately 1-20 micron band, as it impacts the study of circumstellar envelopes. The molecular bands within this region contain an enormous amount of information, especially when observed with sufficient resolution to obtain kinematic information. In a single spectrum, it is possible to resolve lines from up to 50 different rotational/vibrational levels of a given molecule and to detect several different isotopic variants. When high resolution techniques are combined with mapping techniques and/or time sequence observations of variable stars, the resulting information can paint a very detailed picture of the mass-loss phenomenon. To date, near-IR observations have been made of 20 molecular species. CO is the most widely observed molecule and useful information has been gleaned from the observed rotational excitation, kinematics, time variability and spatial structure of its lines. Examples of different observing techniques are discussed in the following sections.
The 'coupled cluster single, double, and triple' (CCSDT) excitation model has been used to ascertain electron correlation energies for 14 different molecules representing a variety of chemical bonds, in conjunction with several methods of this type 'CCSDT-x', which include only an approximate treatment of connected triple excitations; these methods encompass CCSDT-1a, -1b, -2, -3, and -4, as well as the novel CCSD(T). While all methods treat the effects of connected triple excitations iteratively, CCSD(T) approaches then perturbationally. For the 14 molecules considered, the CCSD(T) method's average error relative to CCSDT is substantially lower than any of the CCSDT-x methods.